The question on Wednesday, from Sen. Ted Cruz, R-Texas, was: "As a matter of law, does it matter if there was a quid pro quo? Is it true quid pro quos are often used in foreign  policy?"

Dershowitz answered, “The only thing that would make the quid pro quo unlawful is if the quo were, in some way illegal.” He added: “If a president does something which he believes will help him get elected in the public interest that cannot be the kind of quid pro quo that results in impeachment.”

He responded at length on Twitter Thursday morning to the ensuing criticism:

Ahead of the vote on Friday afternoon on whether to call witnesses at President Donald Trump's impeachment trial, GOP Senate leaders believe they will have just enough votes to block additional testimony and documents.

In order for witness testimony to be approved, four Republicans in the Senate would need to vote alongside all Democrats.

So far, only Sen. Mitt Romney of Utah, has indicated he will vote in favor of witnesses, and Sen. Susan Collins of Maine, has said it is likely she will, too. Sen. Lisa Murkowski of Alaska has hinted at an interest in hearing from witnesses but has not provided a strong indication of how she will vote.

Read the story.

In the latest episode of Article II, Steve Kornacki talks to Leigh Ann Caldwell, NBC News correspondent covering Congress, about the first round of the question-and-answer period in the Senate trial.

The two discuss:

• The Democrats’ effort to convince their fellow senators to call new witnesses in the trial.
• The Republicans’ strategy to argue that the president’s conduct is not impeachable.
• Where the math in the Senate stands on witnesses as we head into day two of Q&A.

It’s so revealing how Republicans’ attitudes about the Ukraine scandal have evolved in just four months.

We’ve gone from Sen. Lindsey Graham, R-S.C., saying evidence of a quid pro quo would be “very disturbing,” to GOP senators not willing to hear from John Bolton, who claims in a new book that President Trump told him he was linking Ukraine’s security aid to investigating the Bidens.

We’ve also moved from some GOP senators being opposed to a president asking a foreign leader to dig up dirt on a political rival — “Look, it is not appropriate for any candidate for federal office, certainly, including a sitting president, to ask for assistance from a foreign country,” Sen. Pat Toomey, R-Pa., said in September — to Trump lawyer Alan Dershowitz now suggesting that a president could do almost anything to win re-election.

That evolution tells you where we’re likely headed.

Get the rest of First Read.

Eight more hours to go. Notable moments so far include deputy counsel Patrick Philbin infuriating Democrats with his argument on campaign finance laws and foreign interference; Philbin saying no one from White House counsel’s office knew about the Bolton manuscript before The New York Times reached out for comment on Sunday; Jay Sekulow’s more sharply partisan tone and his call for witnesses, including the Bidens, Schiff and the whistleblower; the Dershowitz argument on quid-pro-quo. 

The mood in and around West Wing appears more positive than 36 hours ago. Officials still feel cautiously optimistic about deflecting calls for witnesses. Caveat: Any news bombshell between now and Friday night could change the game. 

Senators start their second day of questions and answers after asking more than 90 questions of House managers and Trump's defense team on Wednesday.

Here's a brief recap of the trial so far:

• Senate passes McConnell impeachment rules after nearly 13 hours of debate.
• Day Two: Democrats begin opening arguments.
• Day Three: Prosecution's presentation continues.
• Day Four: Democrats wrap up case.
• Day Five: Trump's legal team begins its defense.
• Day Six: Defense team's presentations continue.
• Day Seven: Trump's defense wraps up arguments.
• Day Seven: Key moments from the question-and-answer phase.