Congress has conducted probes into all kinds of issues, including: The Klu Klux Klan (1871-1873), the sinking of the Titanic (1912), the attack on Pearl Harbor (1945-1946), and organized crime (1950-1951).

Here are some of the most notable Congressional probes, as we await Comey’s testimony in the Congressional investigation into the Trump campaign’s ties to Russia.

1923-1924: The Teapot Dome scandal investigation (Senate Committee on Public Lands and Surveys)

In April 1922, the Wall Street Journal reported that Interior Secretary Albert Fall had bypassed the competitive bidding process in leasing a U.S. naval petroleum reserve field at Teapot Dome, Wyoming, to a private company.  Few people thought that the Senate probe would uncover much, so a junior senator, Montana’s Thomas Walsh, was picked to lead it. The investigation was long, but it successfully uncovered Fall’s shady deals. Fall ended up with the dubious distinction as the first Cabinet member convicted and imprisoned for a major crime committed while in office. Walsh became a national hero, and the phrase “Teapot Dome” became shorthand for government corruption. 

1941: The Truman Committee (Senate Committee to Investigate the National Defense Program)

Missouri Sen. Harry S. Truman rose to national prominence for his tenacious investigation of defense contracting. His originally low-budget committee to look into defense industry corruption and waste grew into a popular and effective effort to root out wrongdoing. By some estimates, his efforts saved the country the equivalent of $230 billion in today’s money in just three years.

1973-1974: The Watergate Committee (Select Committee on Presidential Campaign Activities)

The Senate committee that investigated the Watergate affair included three Republicans and four Democrats who had subpoena power and a mandate to investigate the DNC break-in as well as “all other illegal, improper, or unethical conduct occurring during the Presidential campaign of 1972, including political espionage and campaign finance practices.” President Richard Nixon initially said he would not allow his aides to testify, citing separation of powers. After Nixon relented, former White House aides testified that Nixon had approved a cover-up and had used a recording system in the White House. The committee subpoenaed the tapes, but Nixon refused to hand them over. (The Supreme Court ultimately ruled in July 1974 that Nixon must hand the recordings over to a special prosecutor.) The committee submitted its final report on June 27, 1974. But the House never voted on articles of impeachment; Nixon resigned on August 9, 1974, shortly after the release of the tapes.

1975-1976: The Church Committee (Senate Select Committee to Study Governmental Operations with Respect to Intelligence Activities)

After journalist Seymour Hersch reported that the CIA had improperly surveilled anti-war activists, the Senate established a committee to look into illegal and unethical practices by federal intelligence agencies. The committee, chaired by Idaho Democratic Sen. Frank Church, ultimately found significant abuses, including the targeting of the anti-war movement and civil rights activists including Martin Luther King, Jr. As a result, Congress approved numerous intelligence community reforms, including passage of the Foreign Intelligence Surveillance Act, which required the executive branch to obtain warrants from a FISA court to conduct surveillance and wiretapping.

1987: The Iran-Contra hearings.  (House Select Committee to Investigate Covert Arms Transactions with Iran and the Senate Select Committee on Secret Military Assistance to Iran and the Nicaraguan Opposition)

In November 1986, a Lebanese publication first disclosed that the United States had secretly sold arms to Iran. By the following year — and two months after the presidentially-ordered Tower Commission Report on the matter was released — the nation tuned in to 41 days of televised joint hearings by both House and Senate Select committees probing the deal, which was shown to be tied to release of American hostages held in Lebanon and to the funding of “contras” fighting the Sandinista government in Nicaragua. The hearings featured high-drama testimony from Lieut. Col. Oliver North, who largely orchestrated the exchange, as well as from former Reagan national security adviser Rear Adm. John M. Poindexter. After initially invoking the Fifth Amendment, North finally testified after receiving limited immunity. North famously called the scheme “a neat idea” and admitted that he had lied to Congress.

1995-1996: The Whitewater hearings. (Senate Special Whitewater Committee)

The Senate’s special committee to investigate Bill and Hillary Clinton’s investment into a failed real estate venture in the Ozarks began hearings in July 1995. The committee met more than 50 times and took depositions from almost 250 people.  The proceedings were characterized by partisan bickering and battles over the release of documents.  Additionally, Democrats blocked Republican efforts to give special immunity to a key witness, former Arkansas banker and municipal judge David L. Hale. In their final report, Republicans on the committee described Hillary Clinton as having a pattern of “concealing, controlling and even destroying damaging information,” although they did not directly charge her of engaging in criminal behavior.  The hearings overlapped with the work of special prosecutor Kenneth Starr, whose probe ultimately led to the uncovering of the Monica Lewinsky scandal .

 2014-2016: Benghazi Investigation (House Select Committee on Benghazi)

A total of eight congressional committees looked into the 2012 assault on a U.S. diplomatic facility and CIA compound in Benghazi, Libya, but some of the most rancorous proceedings came from the House’s Select Committee on the matter. The GOP-led panel was formed on a mostly party-line vote in May 2014 and held its first hearing in September. Democrats accused Republicans of manufacturing the controversy to damage onetime Secretary of State and soon-to-be Democratic presidential candidate Hillary Clinton. (In September 2015, Republican Majority Leader Kevin McCarthy famously said Clinton’s “numbers are dropping” because “we put together a Benghazi special committee, a select committee.”) Clinton testified before the panel on October 22, 2015, in a marathon day-long session.  Republicans  released their final report in June 2016, finding no new evidence of wrongdoing by Clinton but sharply criticizing her State Department’s handling of security protocols.

— Carrie Dann

After the public portion of Comey's testimony came to an end, Senators Burr and Warner appeared before the press to give brief statements. 

Burr highlighted that the testimony was an important part of the Senate Intelligence Committee's investigation in Russia's election interference. 

"This is nowhere near the end of our investigation," Burr said, adding that he hopes to work with Special Counsel Robert Mueller "to work out clear pathways for both investigations – his and ours – to continue."

Warner said he was proud of how all the members of the committee approached the questioning.

"Even if we may have disagreements on where all these questions may lead, the one message that I hope all Americans will take home — is recognizing how signification the Russian interference in our electoral process was. How it goes to the core of our democracy," Warner said.

— Liz Johnstone

The White House tapped the Republican National Committee to handle the rapid response to Comey's testimony Thursday, a source familiar with the White House's planning told NBC News yesterday.

The RNC's communications department was poised and ready, firing off emails with talking points while Comey's testimony played out live.

Shortly after the Senate hearing began, the RNC sent an email emphasizing that Comey said the president didn’t direct him to halt the FBI’s Russia investigation. His answer came in response to early questions from Sen. Richard Burr.

The RNC then quickly fired off another release with the title “Attorney General Lynch Attempted To Influence Clinton Investigation.” That missive referred to Comey’s testimony, again in response to Burr’s questions, in which he said Lynch asked him not to call his investigation into Clinton’s emails an “investigation,” but to refer to it as a “matter.”

That “confused me and concerned me,” Comey said.

The RNC also drilled down on Sen. Marco Rubio’s question about why Comey didn’t tell authorities sooner of his concerns about the president’s questions.

An email from the RNC had this response: “Well… Comey finally answered: ‘I don’t know.’”

Just before Comey finished testifying publicly, the RNC declared in an email subject line "James Politi-Comey," and pointed out that he said he'd leaked his memos to a friend. 

— Joy Y. Wang

Sen. John McCain spent a long and confusing seven minutes trying to suggest the FBI has a double standard because they weren't investigating Hillary Clinton while examining Russia's interference in the 2016 election. 

Trump campaign aides had repeated contact with Russian officials, and are at the center of the investigation; there is no evidence or even reports Clinton's aides or allies did the same.

With that, the public questioning concluded as senators head into a classified briefing with Comey, where they'll surely dig into some of the issues they couldn't talk about in public.

— Jane C. Timm

"Do you believe you would have been fired if Hillary Clinton had become president?" Sen. Joe Manchin asked.

The pointed question led Comey to pause and consider the possibility. 

"That’s a great question, I don’t know. Yeah, I don’t know," he said.

Pressed again on whether he had considered the possibility, Comey again demurred.

"I knew it was going to be very bad for me personally and the consequences of that might have been. If Hillary Clinton was elected I might have been terminated," he said. "I don’t know. I really don’t."

— Joy Y. Wang

By saying that President Donald Trump invited him to the January 27 dinner at lunchtime that day, former FBI Director James Comey’s account puts the invitation one day after Former Acting Attorney General Sally Yates  first alerted the White House about her concerns about National Security Adviser Michael Flynn. 

This is the dinner during which Comey said Trump asked the FBI director for loyalty, making Comey feel like his job was being held over him. 

The Oval Office meeting during which Trump asked Comey to lay off Flynn came weeks later on Feb 14.

— Ken Dilanian

At the end of his opening remarks, James Comey said he was sorry he wasn't able to say goodbye to his fellow FBI colleagues when he was fired. Well, he may have the opportunity to do so today.

A committee source tells me those people sitting to Comey's right hand side are FBI officials here on their own time to support their former director.  

— Marianna Sotomayor

The hearing has begun. We're listening to five minute opening statements from Republican Senator Richard Burr, Senate Intelligence Committee chair, and Democratic Sen. Mark Warner, the vice chairman. 

Addressing Comey, Burr said, "Your statement also provides texture and context to your interactions with the President, from your vantage point, and outlines a strained relationship. The American people need to hear your side of the story, just as they need to hear the president’s description of events."

Warner began by stating the committee's purpose in investigating Russia's efforts to influence the election.

“To be clear this investigation is not about litigating the election," says Warner. “We are here because a foreign adversary attacked us right here at home.”

Warner goes onto say that Russian cyber attacks were intended to “hijack our most important democratic process: our presidential election.”  Warner says the cyber raids sought to “undermine public faith in a process, in ourselves.” 

He reiterates the point that the Congressional investigation is not about politics at the end of his statement: “This is not a witch hunt, this is not fake news.”  Warner’s opening statement seems to be responding to President Trump’s criticism and his comments on Twitter that the Russia investigation is nothing more than a partisan “witch hunt.”

Next, Comey will be sworn in and read portions of his testimony. The question and answer question will last just one round, now, according to Burr. Second questions will happen in the closed door session. 

— Liz Johnstone, Meredith Mandell

A source tells NBC News' Alex Moe that Comey has arrived to the hearing room on Capitol Hill and went into a hold room. 

Senators Burr and Warner are meeting with Comey now ahead of the hearing in a backdoor inside the hearing room. 

As a private citizen, Comey may choose to speak to Congress or the public about many topics, including aspects of his tenure in government, but there’s a slew of things he can’t get into and may decline to answer Senators questions about.

• He MAY be restricted from discussing topics in the open Russia inquiry, at the potential request of the FBI or DOJ Special Counsel;
• He WILL be restricted from disclosing information about FBI investigations that has a “substantial likelihood” of prejudicing any future case or proceeding
(per Department of Justice guidelines); 

• He WILL be restricted from disclosing classified information (per federal law, 18 USC 798); 

• He WILL be restricted from confirming the existence of investigations that have not already been confirmed by the FBI or DOJ 
(per DOJ guidelines). 


— MSNBC Legal Unit

A senior White House aide tells NBC News President Trump will monitor the Comey testimony, as time permits, in a White House dining room with his legal team and some of his closest advisers. The president’s public schedule is wide open this morning. 

Trump is scheduled to leave the White House at later in the morning for a speech to a friendly crowd of evangelicals at the Faith and Freedom Coalition’s Road to Majority Conference. He’ll be back at the White House after that for an infrastructure summit with mayors and governors.

— Peter Alexander

The nation isn't buying the president’s story when it comes to the firing of James Comey, according to a new survey released a day before the former FBI Director testifies in front of the Senate about his dismissal.

A majority of Americans, 61 percent, think President Trump fired Comey “to protect himself,” according to the ABC News/Washington Post poll. Just 27 percent of respondents said the president’s firing of the head of the nation’s top law enforcement agency — while it was investigating his presidential campaign’s ties to Russia — was “for the good of the country.”

A slimmer majority, 56 percent, said they believed the president was trying to interfere in the federal investigation into his campaign’s ties to Russia. And 34 percent of survey respondents said the president was cooperating with that investigation. 

Heading into what’s sure to be some of the most highly anticipated Senate testimony this year, Americans don’t trust their president or the former head of the FBI. Just 21 percent say they trust the president, while 36 percent say they trust Comey.

—Jane Timm