Senate Majority Leader Mitch McConnell, leaving the floor ahead of the vote to confirm Judge Neil Gorsuch to the Supreme Court, expresses optimism that a stopgap funding measure will have bipartisan support. (Aaron P. Bernstein/Reuters)

Congress is off for two weeks, and when lawmakers return, they will quickly face a critical deadline to keep the government open. But in an unusual development on Capitol Hill, where budget brinkmanship has become a reliable expression of political dysfunction, nobody is threatening to shut the government down.

Instead, Republicans and Democrats appear to be working together to keep the lights on in Washington. Aides in both parties said negotiations are underway on a stopgap funding measure that both sides could support, one that sidesteps such political land mines as President Trump’s request for new funding to build a wall on the U.S.-Mexico border.

Even Senate Majority Leader Mitch McConnell (R-Ky.) sounded a note of optimism as his chamber adjourned for its Easter break. He told reporters that bipartisan support would be needed not only for the stopgap measure, which would fund the government through September, but also for the fiscal 2018 spending bills needed to fund government operations in the months beyond.

(Video: Jenny Starrs/Photo: Jabin Botsford/The Washington Post)

None of those bills “can be done one party only,” McConnell (R-Ky.) said. “All of that will have to be done on a bipartisan basis. And I think — the Democratic leader can speak for himself — but I’m confident he looks at it the same way.”

The bipartisan bonhomie marks a refreshing break from the dark days of spending fights that descended on the Capitol after the 2010 elections swept a wave of hard-line conservative tea party candidates into office.

Since then, the GOP’s right flank has taken an aggressive stance on cutting federal spending, threatening repeatedly to shut down the government or even default on the nation’s debts in hopes of securing an agreement to slash spending. That has forced Republican House leaders to turn to Democrats for the votes to push must-pass measures over the finish line to raise the federal debt limit and finance the government.

The difference this time is that Republican leaders are turning to Democrats from the get-go, a decision that will produce less drama in the halls of Congress but is likely to make it much harder to craft a budget that matches Trump’s ambitions on an array of fronts, from the border wall to a big increase in defense spending.

In an interview Friday, McConnell told The Washington Post that he is unsure how to square that circle. But he was insistent that Democrats need to play a part in the negotiations.

“It seems to me that neither side benefits from sort of a government-shutdown scenario again in September,” McConnell said. “Exactly how we get from here to there, I couldn’t tell you today.”

The spending measure expires April 28 — just four days after lawmakers return from their Easter break.

House Republicans are bitterly divided and aimless after the collapse of a plan by House Speaker Paul D. Ryan (R-Wis.) to rewrite the Affordable Care Act, otherwise known as Obamacare. Still angry over that grueling battle, the right wing of Ryan’s caucus is not expected to support a measure to keep the government open past the April deadline, though that is far from settled.

So Ryan has turned for help to House Minority Leader Nancy Pelosi (D-Calif.). Last week, Pelosi said lawmakers from both parties were working well together to craft a stopgap spending measure. But she predicted that the measure’s fate would ultimately be in Trump’s hands.

Trump, for example, could refuse to sign a funding measure that doesn’t include money to build a wall along the U.S.-Mexico border. Such funding is a non-starter with Democrats, as are any other policy changes that could be construed as a win for the president.

“Members of Congress know what they can pass. Maybe the White House doesn’t,” Pelosi said. “And that’s — that line of communication is where you might see some — more difference of opinion than even between Democrats and Republicans in the Congress.”

If they clear the April 28 hurdle, Republican lawmakers and aides are already worrying privately that a larger spending battle looms over Trump’s budget request for the fiscal year that begins Oct. 1.

Most Democrats and many Republicans have roundly criticized Trump’s plan to increase the defense budget by $54 billion — money that would be carved directly out of the budgets of domestic agencies, including the Environmental Protection Agency, the State Department and the Agriculture Department.

Rep. Mark Sanford (R-S.C.) said Trump’s request has put Republicans in a difficult situation. Trump has promised voters that Republicans will expand the military, regain control of government spending and overhaul the federal government without cutting safety-net programs for older and poorer Americans — a promise many lawmakers see as mathematically impossible.

Conservatives like Sanford say Washington will never get its fiscal house in order without reining in spending on such popular programs as Medicare, Social Security and Medicaid, which together make up about half of federal spending.

“What you have is a mousetrap,” Sanford said. “Back home, you’ve got the mayor of North Charleston riding around in a Meals on Wheels truck saying, ‘I don’t think we should cut this’ — and he was an early Trump supporter.”

The White House has been closely monitoring preliminary talks about fiscal 2018 spending bills, according to Republican aides who were granted anonymity to discuss private negotiations.

Last week, Ryan said he is optimistic about budget deals because there is a Republican in the White House.

“The good news is we don’t have to deal with the Obama administration,” Ryan told reporters at his weekly news conference. “We don’t have to fight an administration that we disagree with on so many issues. We are now working with an administration we agree with.”

But it’s far from clear that Ryan’s rank-and-file will line up behind him. Conservatives are still angry that Ryan persuaded them to try to roll back the Affordable Care Act by using a special budget procedure known as “reconciliation” that would have made it easier to push a bill through the Senate.

The repeal effort unraveled when Ryan could not build a coalition of moderates and conservatives large enough to approve a rewrite of the health-care law. Many conservatives are wary of making the same mistake in the 2018 spending measure.

House Freedom Caucus Chairman Mark Meadows (R-N.C.) — one of the holdouts on health care — was among several conservatives who warned recently that they wouldn’t support a spending bill just to avert a shutdown. Meadows said conservatives are particularly concerned about where any budget bill sets overall spending levels for government agencies.

“Now you’re going to be setting top-line numbers, which you appropriate to,” Meadows said. “That will have a unique dynamic, let’s put it that way.”

Hard-liners are also expected to balk at efforts to use reconciliation procedures to advance a comprehensive rewrite of the tax code, another top priority for Ryan and Trump. These lawmakers say they will not necessarily support a tax overhaul if it is accompanied by higher spending.

“I think it’s more important that we take a look at the budget and make sure that it meets the principles we’re trying to move forward,” said Freedom Caucus member H. Morgan Griffith (R-Va.).

Griffith said any spending increases must be paired with cuts elsewhere or with policies to rein in spending on Social Security and Medicare, which is rising rapidly as the baby-boom generation retires.

A large number of conservatives voted against each of the last three spending measures over those same concerns. The most consequential fight came in 2015, when Republican leaders were forced to turn to Democrats to avert a government shutdown. The result was a two-year compromise that increased spending across the board and ensured equal funding for domestic and military programs.

That agreement is set to expire at the end of September, and GOP leaders have begun to fret quietly over what will happen.

Meanwhile, Democrats are eagerly laying plans to swoop in with a budget compromise if Ryan cannot solve the problems that have riven the lower chamber for the past six years.

Sen. Bernie Sanders (I-Vt.), who serves on the Senate Budget Committee, said last week that Democrats would offer a spending blueprint to counter Trump’s budget request.

“It has to be defeated and we will come up with alternatives.” Sanders said. Democrats will not support “tax breaks for millionaires . . . and cuts to programs that people desperately need.”