Donald Trump's escalating feud with his top Senate partner undercuts the president's stalled agenda on tax overhaul and budget while prompting swift pushback from Republican senators who have lined up squarely behind Majority Leader Mitch McConnell.

Trump launched a barrage of criticism at McConnell over the collapse of the seven-year GOP campaign to repeal and replace Barack Obama's Affordable Care Act and even suggested on Thursday that the Kentucky Republican might have to rethink his future as leader if he doesn't deliver on the president legislative lineup.

"Well, I tell you what, if he doesn't get repeal-and-replace done and if he doesn't get taxes done, meaning cuts and reform, and if he doesn't get a very easy one to get done, infrastructure, if he doesn't get them done, then you can ask me that question," the president told reporters in Bedminster, New Jersey, where he is in the midst of a 17-day break from Washington.

Story continues below advertisement

Trump on Thursday called McConnell's failure to pass an "Obamacare" repeal last month "a disgrace." On Friday, Trump retweeted headlines from "Fox & Friends" about his verbal assault on McConnell and possible fallout for GOP senators who criticize the president.

Also: Trump tweets U.S. 'locked and loaded' as North Korea readies missiles

There was no immediate response from McConnell's office. But members of the Republican caucus praised McConnell.

"Passing POTUS's legislative agenda requires a team effort. No one is more qualified than Mitch McConnell to lead Senate in that effort," tweeted Texas Sen. John Cornyn, the No. 2 Republican in the Senate.

"From health care to tax reform to infrastructure, tough issues to tackle this fall and none better than SenateMajLdr to get a good outcome," tweeted Sen. Bob Corker, R-Tenn., chairman of the Foreign Relations Committee.

A sitting president openly turning on a Senate majority leader of his own party in such a fashion is practically unheard of — yet another norm destroyed since Trump's rise on the political scene. And while the fighting words might elate Trump's core supporters, they can only hurt broader Republican efforts to move major legislation this fall on taxes and spending while preparing for congressional elections next year against energized Democrats who are rallying to retake the House. Republicans control both chambers, but the Trump factor in many races remains a mystery.

Trump's comments came after he spent two days slamming McConnell on Twitter, writing Thursday morning that after "screaming" about repealing and replacing Obamacare for seven years, McConnell "couldn't get it done." Several hours later, the president's tone took a motivational turn as he exhorted McConnell to "get back to work" and pass bills. "You can do it!"

Story continues below advertisement

The presidential megaphone amplified the McConnell-bashing that's been snaking through conservative media: Breitbart News, Fox News' Sean Hannity and radio host Rush Limbaugh are among those who have vilified the leader after the Senate's failure on health care. They represent a segment of the Republican electorate, including some major donors, who are out to punish what they see as a "do-nothing Congress" that has hampered the president's work.

McConnell is "a coward who leads from behind," "spineless," and a lifelong "political animal" of the sort Trump wants to eject from Washington, said Doug Deason, a major donor based in Texas. Deason said he decided months ago not to give money to any Republicans up for re-election next year unless they can pass Trump's priorities.

Trump and his supporters love such political brawls, and the McConnell tussle potentially shores up the president's base at a time when it is showing signs of weakening support. After all, he is picking on a part of government with lower approval ratings. But other Republicans saw Trump's moves as counterproductive.

Even Newt Gingrich, a Trump backer and informal adviser who formerly served as speaker of the House, criticized the dispute.

"You saw Mitch McConnell say something, you saw Trump say something, when it's obviously better for them to learn not to do that," Gingrich said. "They have to work together. Governing is a team sport."

After the failure on health care, McConnell and other Republican leaders, including top White House economic officials, are determined to move on to overhauling the tax code with the hope of passing cuts by the end of the year — a daunting challenge. McConnell has made clear he has little interest in revisiting the health care fight.

Story continues below advertisement

Trump, 71, and McConnell, 75, have never been easy allies, even though the senator's wife, Elaine Chao, is the president's transportation secretary. McConnell only met Trump for the first time in 2013, when he made a pilgrimage to Trump Tower in New York to ask the businessman for campaign money.

But McConnell quickly boarded the Trump train once the mogul secured the GOP nomination, and unlike House Speaker Paul Ryan and others, he never wavered. He's paid numerous visits to the White House and travelled with Trump in March to Louisville. That Trump rally predated all of Congress' attempts to redo health care, and the president urged the crowd to "be nice" to McConnell.

Fast forward to August, with the Senate on recess after the collapse of the GOP health care bill.

McConnell touched a nerve by telling an audience in his home state that Trump had "not been in this line of work before" and had "excessive expectations about how quickly things happen in the democratic process."

What followed was a "tense" phone call between the two men, according to a person familiar with the exchange but not authorized to speak publicly about a private discussion, and then a presidential Twitter screed.