The Republican Party is at the brink of breaking out into open warfare with itself after months of straining to keep its internal divisions under control.

After shaking up his own leadership team out of frustration with its performance, Trump is firing warning shots at Capitol Hill and openly criticizing Senate Majority Leader Mitch McConnell Addison (Mitch) Mitchell McConnellGraham: GOP will confirm Trump's Supreme Court nominee before the election Trump puts Supreme Court fight at center of Ohio rally The Memo: Dems face balancing act on SCOTUS fight MORE (R-Ky.).

Speaking at a rally in Phoenix Tuesday evening, Trump ramped up pressure on congressional leaders to deliver on one of his top campaign promises: a wall along the U.S.-Mexico border.

“If we have to close down our government, we’re building that wall,” he told the crowd.

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House Freedom Caucus Chairman Mark Meadows (R-N.C.), who was close to Trump during the 2016 campaign, is warning that Speaker Paul Ryan Paul Davis RyanKenosha will be a good bellwether in 2020 At indoor rally, Pence says election runs through Wisconsin Juan Williams: Breaking down the debates MORE (R-Wis.) and McConnell could lose their jobs if they fall short on tax reform and funding the U.S.-Mexico border wall.

“Bottom line: if Paul Ryan and Mitch McConnell can get the president’s agenda done, they can probably keep their jobs,” Meadows said in an interview.

“If Paul Ryan and Mitch McConnell can’t get the president’s agenda done, I don't know that they get to keep theirs, nor do I know if I get to keep mine. We’ve got to deliver. It’s critically important we do that in a way that conservatives have long espoused,” he said.

GOP leaders, meanwhile, are scrambling to deflect blame.

Ryan is highlighting the number of bills the House GOP has passed, a tacit complaint that it is the Senate where Republican legislation is dying.

The House is focused on getting the Republican agenda executed, Ryan said at a town hall event on Monday.

“I wish I could say the Senate was moving as fast. Of the 300-plus bills we passed out of the House, 260 are still sitting in the Senate,” Ryan said. “So we got a ways to go. And we've got to get more work done.”

McConnell, behind the scenes, has been critical of Trump, who has unleashed a torrent of controversies since moving into the White House. In an explosive story published Tuesday, The New York Times reported that McConnell has privately expressed uncertainty over whether Trump can salvage his presidency.

Tensions between McConnell and Trump are at a boiling point.

Trump yelled at McConnell in a profanity-laced phone call on Aug. 9, during which he blamed the GOP leader for failing to pass a ObamaCare repeal bill and for not curbing congressional investigations into allegations of collusion between the Trump campaign and Russia, according to The Times.

Trump has also taken shots in recent weeks at Republicans who oppose his agenda, namely Arizona Sens. John McCain John Sidney McCainBiden's six best bets in 2016 Trump states Replacing Justice Ginsburg could depend on Arizona's next senator The Hill's Morning Report - Sponsored by Facebook - Washington on edge amid SCOTUS vacancy MORE, who voted against the healthcare bill, and Jeff Flake Jeffrey (Jeff) Lane FlakeJeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Republican former Michigan governor says he's voting for Biden Maybe they just don't like cowboys: The president is successful, some just don't like his style MORE, who disagrees with him on trade and immigration.

The president complained at the Phoenix rally that the ObamaCare repeal bill fell one vote short of advancing, a clear reference to McCain, and attacked Flake as “weak on borders, weak on crime,” without naming him specifically.

All of the friendly fire comes after one of the most difficult weeks of Trump’s presidency, in which he came under fire for saying both sides deserved blame for the violence that broke out in Charlottesville, Va., where white supremacists and those protesting them clashed.

And it comes ahead of a difficult month for Republicans that promises to divide them further.

Republicans must approve legislation raising the nation’s borrowing limit by Sept. 29, a battle that appears set to pit conservatives such as Meadows against both Treasury Secretary Steven Mnuchin Steven Terner MnuchinShutdown clash looms after Democrats unveil spending bill Lawmakers fear voter backlash over failure to reach COVID-19 relief deal United Airlines, unions call for six-month extension of government aid MORE, who wants a clean debt bill, and congressional GOP leaders, who are inclined to go along with him.

The administration says Congress should approve a “clean” hike to the borrowing limit, while conservatives want to add provisions to cut or restrict future spending.

“Why would we put a clean debt ceiling increase with absolutely no reforms whatsoever on the desk of a Republican president when we wouldn't even do that with a Democratic president?” conservative Rep. Dave Brat (R-Va.) told The Hill on Tuesday.

Congress also must approve legislation to keep the government funded to prevent a shutdown by the end of September.

Most Republican lawmakers want to avoid a shutdown, but Trump has suggested it could be helpful to have one. He also sees the government-funding bill as a way to secure funds for the border wall — a proposal that is backed by Ryan but has its critics in the GOP.

All Republicans are facing pressure to score some wins this fall.

After Republicans won control of both Congress and the White House, Ryan vowed to go big and bold.

“The opportunity is now here. The opportunity is to go big, go bold and to get things done for the people of this country,” he said.

Yet besides the confirmation of Supreme Court Justice Neil Gorsuch, GOP leaders have accomplished little on Trump’s wish list during his first 200 days in office.

The lack of progress has been felt in the West Wing, where chief of staff Reince Priebus, chief strategist Stephen Bannon and press secretary Sean Spicer have all lost their jobs.

The question looming over Congress is whether the axe will start falling on Capitol Hill after another half-year of legislative disappointments.

No Republican in the House has the support to defeat Ryan, and Meadows is not putting himself forward as a candidate.

Ryan and Meadows also speak frequently, and the Freedom Caucus leader was careful to note that he himself could be replaced if there are not successes this fall.

A Ryan spokesperson declined to comment for this story.

But a top House GOP source said the lower chamber has passed a number of bills this year with little media coverage or fanfare. Many of those, including bills overhauling ObamaCare, the Dodd-Frank law and partial funding for Trump's border wall, have been ignored by the Senate, the source said.

House Republicans have created a website to highlight their work during the first seven months of the Trump administration: Didyouknow.gop.

In the Senate, McConnell appears safe. Republican lawmakers largely rallied to his defense after Trump tweeted criticism of their leader.

McConnell’s allies say he has rock-solid support in the Senate GOP conference. Even after the contentious healthcare debate, which left a few senators — such as Sen. Ron Johnson Ronald (Ron) Harold JohnsonThis week: Supreme Court fight over Ginsburg's seat upends Congress's agenda GOP set to release controversial Biden report Democrats fear Russia interference could spoil bid to retake Senate MORE (R-Wis.) — frustrated over the process, no one openly called for him to step down.

Similarly, Trump’s attacks on Flake, who is up for reelection next year, have not gone over well with the GOP conference.

A McConnell spokesman declined to respond on the record.

Still, there’s no question Republicans are feeling the heat.

The Times reported Tuesday that Trump and McConnell have not spoken to each other in the weeks since the president punched back at McConnell for suggesting he had “excessive expectations” about the legislative process.