The Fix's Amber Phillips explains the tight deadlines Congress faces this fall, and how President Trump's shutdown threat over funding his border wall and his criticism of the debt ceiling "mess" threaten their agenda. (Jenny Starrs/The Washington Post)

President Trump is strategically separating himself from Republicans in Congress, an extraordinary move to deflect blame if the GOP agenda continues to flounder.

Trump deepened the fissures in the party on Thursday when he accused the top two leaders on Capitol Hill of mismanaging a looming showdown over the nation’s borrowing authority. Republican lawmakers and aides responded to the president’s hostility with broadsides and warnings of their own.

Frustrated by months of relative inaction at the other end of Pennsylvania Avenue and emboldened by his urge to disrupt the status quo, Trump is testing whether his own political following will prove more potent and loyal than that of his party and its leaders in both houses of Congress.

The growing divide comes at an inopportune moment for Washington, however. In addition to having to raise the debt ceiling to avoid a fiscal crisis, Republicans face September deadlines to pass a spending bill to avert a government shutdown, as well as pressure to fulfill a key Trump campaign promise to rewrite the nation’s tax laws.

Behind the scenes, some Republican staff members described a more functional relationship between aides and lawmakers on Capitol Hill and White House officials. But in public, Trump is waging war against lawmakers. With a pair of morning tweets, he said he asked Senate Majority Leader Mitch McConnell (R-Ky.) and House Speaker Paul D. Ryan (R-Wis.) to include a debt-ceiling increase in a recent veterans bill.

Senate Majority Leader Mitch McConnell (R-Ky.) speaks during the Kentucky Farm Bureau’s Country Ham Breakfast on Thursday. (Timothy D. Easley/Associated Press)

“I requested that Mitch M & Paul R tie the Debt Ceiling legislation into the popular V.A. Bill (which just passed) for easy approval,” he wrote. “They . . . didn’t do it so now we have a big deal with Dems holding them up (as usual) on Debt Ceiling approval. Could have been so easy — now a mess!”

In a later tweet, the president slammed McConnell for not being able to pass a bill to repeal and replace the Affordable Care Act. “That should NEVER have happened!” he wrote.

Trump is railing against Republicans because he thinks it will help him politically down the road, for instance during a 2020 reelection bid, said one outside adviser to the White House.

If Republicans lose the House in the 2018 midterm elections, as several White House advisers have warned the president, Trump can say, “See, I told you these guys wouldn’t get anything done. I’ve been saying this for months. They’re not following my agenda,” said the adviser, who spoke on the condition of anonymity to describe private talks.

Roger Stone, an ally of and former political adviser to Trump, put it this way: “The Trump brand and the Republican brand are two different things. What happened the last time the establishment tried to face him down? They got crushed.”

If Republicans lose the House, however, Trump could face greater peril than a difficult 2020 election: a Democratic majority eager to pursue impeachment and with subpoena power to conduct investigations.

Senate Majority Leader Mitch McConnell (R-Ky.) and President Trump's relationship is fraying amid Trump's repeated public attacks and controversial statements. (Jenny Starrs/The Washington Post)

For many GOP lawmakers, the justification for not fully breaking from Trump has been the promise of trying to salvage key parts of the party’s agenda. But now, they are increasingly resigning themselves to the reality that they will be largely on their own. One Senate GOP aide likened it to “being handed the keys to the car.”

As a result, they have grown increasingly hostile toward the president.

“It doesn’t help at this point, with a September coming up that is very consequential, to be throwing rocks at one another,” said Rep. Tom Cole (R-Okla.). He added: “You don’t, I think, do a lot of good by torching your teammates, particularly by name, individually.”

Said the Senate GOP aide, who spoke on the condition of anonymity to be candid: “The sense you get is ‘We’re going to have to figure this out.’ We’re just going to assume we’re not going to get any help from the White House.”

Some White House aides have shown little sympathy toward GOP lawmakers who have made harsh remarks about Trump. Asked Thursday to respond to recent comments by Sen. Bob Corker (Tenn.) doubting the president’s competence and stability to lead, White House press secretary Sarah Huckabee Sanders responded, “I think that’s a ridiculous and outrageous claim and doesn’t dignify a response from this podium.”

The relationship between Trump and McConnell, meanwhile, has become increasingly acerbic in recent weeks, in private and public. But as details have surfaced in news reports, McConnell has tried to project unity even as some Republicans have said tensions are still raw.

In remarks Thursday morning at the Kentucky Farm Bureau’s annual Country Ham Breakfast, McConnell praised the president and his administration for making strides on regulatory reform, the Supreme Court and looking out for rural Americans.

But he acknowledged differences on trade, saying he was “a little concerned” about some of Trump’s protectionist rhetoric. He also cracked a joke that underscored the challenges he faces with a narrow majority in the Senate.

“I’m often asked, ‘What is being the majority leader of the Senate like?’ ” he said. “The best answer I’ve been able to think of is, ‘It’s a little bit like being a groundskeeper at a cemetery. Everybody’s under you, but nobody’s listening. That’s what you get with 52-48.’ ”

McConnell sees a 2018 Senate map ripe with opportunities to expand the GOP majority. For this reason, Republicans in his orbit have been particularly pained by Trump’s attacks against Sen. Jeff Flake (R-Ariz.), a critic of the president who is up for reelection. They see the leader of their party, Trump, potentially sabotaging a chance to make it easier to pass the legislation he has complained about stalling.

The Trump administration has warned that Congress must raise the federal debt limit before October to avert a fiscal crisis. The government spends more money than it brings in through revenue, and it borrows money to cover the difference by issuing debt.

During an event in Everett, Wash., on Thursday, Ryan said he is confident that Congress willraise the debt limit and avoid a federal default.

“We pay our debts in this country, and we’ll continue to do so,” he said. “I’m not worried that’s going to get done, because it’s going to get done.”

Ryan acknowledged discussions about attaching the debt issue to the veterans bill, but said the maneuver ultimately “wasn’t available to us.”

Several House aides expressed exasperation Thursday about Trump’s claim regarding that proposal. They called that a misrepresentation of what had actually happened: White House and congressional aides had informally discussed the possibility that the Senate could attach a debt-ceiling extension to a House-passed veterans bill in late July, but it was never clear that the Senate would act before the House was scheduled to break for the summer — and many conservative House Republicans had warned GOP leaders not to pursue the maneuver.

Trump’s threat this week to shut down the government if a spending bill to keep it running past the end of next month does not include funding to construct a wall along the U.S.-Mexico border has compounded worries about the September to-do list.

“We don’t need a government shutdown. That never ends well,” Flake told Fox News Channel on Thursday. “We don’t save money doing it.”

The House Freedom Caucus stands to play a pivotal role in the fall’s legislative drama. On one hand, the bloc of hard-liners has been among the most fervent backers of Trump’s agenda, and its top leader, Rep. Mark Meadows (N.C.), frequently consults with the president. On the other hand, the caucus and other conservatives have been reluctant to compromise on their principles to accomplish it — at least not without a fight.

“Republicans control the House, Senate, and White House,” Rep. Mark Walker (N.C.), a member of the Republican Study Committee, wrote in an opinion piece published this month. “Any legislation signed into law needs to reflect unified government.”

Congressional Democrats are expected to stand firmly in opposition to Trump’s attempt to secure more federal funding for the border wall, as they did in the spring during similar spending talks.

On the debt limit, Democrats are taking a more hands-off approach, thinking the issue is entirely up to Republicans to resolve, given that in the past they called for spending reductions to be coupled with any debt-limit increases.

Some congressional aides are anticipating that Trump will hold a White House meeting with top House and Senate leaders shortly after lawmakers return from their recess.

If a meeting is held, it would be the first face-to-face exchange between Trump and House Minority Leader Nancy Pelosi (D-Calif.) since the president hosted a cocktail reception for top lawmakers in late January. The last time he saw Senate Minority Leader Charles E. Schumer (D-N.Y.) in person was the day after that reception, at a meeting about Supreme Court nominees.

Some Republicans hope that private negotiations on tax reform, the debt ceiling and keeping the government running won’t be weighed down by ugly public feuds.

One senior Republican involved in the process said Thursday that a relatively drama-free extension of the debt limit and a resolution to keep the government open until the end of the year are both likely to pass next month, with discussions about a border wall pushed into the next round of budget negotiations.

A second Republican, who has spoken with the president, said Thursday that Trump sees benefits from fighting GOP leaders but is not yet convinced that a showdown over a wall in September is necessary and is open to hearing options about how to proceed. The Republicans spoke on the condition of anonymity to be candid.

Still, the long-term political upside that many in Trump’s inner circle see in going after congressional Republicans and the hard-line stances Trump is fond of taking are expected to complicate the delicate talks. They also raise the possibility that Trump will never ease up in his attacks.

“This is where the base already was. They hate Washington,” said Barry Bennett, a former Trump campaign adviser. He added: “They don’t need the president to tell them that Congress isn’t doing its job. They already understand that.”

Ed O’Keefe, Damian Paletta and Robert Costa contributed to this report.