A partial federal government shutdown began Tuesday morning as a deadlocked Congress failed to reach an agreement on a short-term funding bill by a 12:01 a.m. ET deadline.
As the clock ticked down to midnight, House Republicans announced that they would try to shift decision-making to a bipartisan conference of lawmakers from both chambers, but Senate Majority Leader Harry Reid immediately rejected that plan.
“We will not go to conference with a gun to our head," he said.
The House requested the conference -- and it again approved its already-rejected short-term spending bill -- in votes after 1 a.m. ET before recessing for the evening.
The Senate will reconvene at 9:30 a.m. ET, and Reid promised to immediately table -- or kill -- the House conference plan first thing Tuesday morning.
House Republicans say they support the conference plan to find some middle ground between the Democratic-controlled Senate's “clean” government funding bill and the GOP-led House's proposal to delay a key part of Obamacare and nix health care subsidies for congressional staffers.
Government officials told agencies to begin executing plans for a shutdown -- the first in 17 years -- shortly before midnight Monday.
“I can’t believe it will go for very long,” Sen. Jeff Flake, R- Ariz., said on MSNBC’s Morning Joe Tuesday morning. “I hope that today or tomorrow that we can open it back up.”
Referring to his House Republican counterparts, he added that, “I think we all share the same goal, certainly to rein in spending and no Republican voted for Obamacare before. But it’s no secret that I haven’t agreed with the tactic or the strategy here. I just don’t think that we should have used this vehicle,” that is, the short-term spending bill.
Flake also said that for the GOP strategy to succeed the Democrats would need to fear a partial government shutdown, but in fact they welcomed it: “The Democrats knew that if there were to be a shutdown, that it would be Republicans who’d take the blame. So you’re threatening to do something that the other side isn’t very fearful of.”
The shutdown will place tens of thousands of federal workers on unpaid furlough while forcing others to work without pay, close national parks and monuments, and disrupt services like food assistance and IRS audits.
Social Security, Medicare and other entitlement payments and national security operations will go on as usual, and -- because of a bipartisan measure passed by both houses of Congress and signed into law by the president late Monday -- members of the military will continue to be paid.
The new insurance "exchanges" mandated by the new health care law also went live even as the shutdown began.
Earlier Monday, the Senate twice rejected House-passed measures that would have delayed key provisions of Obamacare while funding the government for an additional few weeks.
Reid said on the Senate floor Monday that Republicans "have lost their minds" by repeatedly voting for "ridiculous policy riders" destined for failure in the Democratically-controlled Senate.
Speaking shortly before the first House vote Monday, House Speaker John Boehner said the measure to delay the mandate was about "fairness."
"I would say to the president: This is not about me," Boehner said. "This is not about Republicans here in Congress. It's about fairness for the American people."
The president spoke by phone Monday to Boehner as well as to other congressional leaders in both chambers, the White House said. His call to Boehner lasted about 10 minutes, an aide said.
The call came shortly after the president urged Republicans to pass a “clean” funding bill rather than tying an Obamacare-delaying provision to the legislation and accused GOP leaders of acting to "save face after making some impossible promises to the extreme right wing of their party."
“One faction of one party in one house of Congress in one branch of government doesn't get to shut down the entire government just to re-fight the results of an election," he said during a statement at the White House.
In an afternoon interview with NPR News, Obama reiterated that any funding measure that involves major changes to Obamacare is a non-starter.
Asked what he can ‘offer’ towards a compromise – especially once the debate shifts to the debt ceiling – Obama insisted he should not have to negotiate over the issue. “I shouldn't have to offer anything,” he told host Steve Inskeep. “They're not doing me a favor by paying for things that they have already approved for the government to do. That's part of their basic function of government, that's not doing me a favor.”
NBC News' Frank Thorp, Luke Russert and Chuck Todd contributed to this report.