Getting Barr through the Senate was difficult enough, with his nomination accruing just 54 votes, including the support of three Democrats — one of the most partisan confirmations of any attorney general.

If Trump were to ditch Barr, or if the attorney general resigned, the Senate would be unlikely to confirm a successor “any time soon,” Cornyn predicted. Republicans are fighting to save their Senate majority and reelect Trump in November, and having to handle a new nominee amid Trump's interference with DOJ would be unwelcome in GOP circles and require vulnerable senators to take a potentially tough confirmation vote.

Since his remarks about Trump’s tweets, Senate Republicans have lavished Barr with support. Barr spoke to Senate Judiciary Chairman Lindsey Graham (R-S.C.) Tuesday, according to a source familiar with the conversation. The attorney general has suggested he is frustrated with some of the president’s comments, but has no immediate plans to leave his post.

If Barr did depart, it's possible Trump would just have an acting attorney general through the remainder of his term if the GOP-led Senate decided against a new confirmation battle.

Graham, along with Senate Majority Leader Mitch McConnell (R-Ky.) and House Minority Leader Kevin McCarthy (R-Calif.) issued a joint statement Tuesday saying Barr has the “highest character and unquestionable integrity.” Their comments came after more than 2,000 DOJ alumni signed an open letter organized by the nonprofit Protect Democracy that called for Barr’s resignation, after the Justice Department revised its sentencing recommendation for Stone, a Trump campaign ally.

The sentencing revision, which prompted the resignation from the case of four career prosecutors, came after Trump tweeted that the original sentence recommendation of seven to nine years was “horrible and very unfair.” The Justice Department insisted the change in the sentencing recommendation was in the works before Trump’s tweet.

Regardless, Barr’s future is uncertain after he went public with his complaints that it’s “time to stop the tweeting about Department of Justice criminal cases.” Trump has dug in further, asserting after Barr’s comments that he has the right to weigh in on cases, and he has declared himself the “chief law enforcement officer.”

Senate Republicans are calling for a cease-fire and trying to impress on Trump that Barr is one of the best allies he could ever have.

“Attorney General Barr is a dedicated public servant who has earned his reputation for character and integrity. I hope the president sees that he, the American people, and the rule of law are well-served by Barr’s work at the Department of Justice,” said Sen. Ben Sasse of Nebraska.

“The attorney general is one of the most capable Cabinet officials I’ve been able to vote for,” said Sen. Chuck Grassley of Iowa, a former Judiciary chairman. “He’s handling the responsibilities of his office with dedication, exceptional transparency and remarkable competence, all without bending to political winds.”

Republican aides said they were puzzled at the dispute, which centers more on tone and temperament than anything else. Unlike the rift between former Defense Secretary Jim Mattis and the president on foreign policy or the drip-drip of scandals of former EPA Administrator Scott Pruitt, Barr is widely seen by Republicans as an effective ally of the president who should be a long-term fixture in Trump’s Cabinet. Sen. Thom Tillis of North Carolina said he envisioned Barr serving “well into President Trump’s second term.”

Meanwhile, Democrats — including the three senators who backed his confirmation — have gradually grown more anxious about Barr’s approach to the job.

Both Sens. Joe Manchin of West Virginia and Doug Jones of Alabama expressed apprehension with the way Barr presented the Mueller report; last week, Sen. Kyrsten Sinema of Arizona said she had “concern” over the way Stone’s sentencing has been handled.

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One Senate Republican, Rand Paul of Kentucky, opposed Barr’s nomination to be attorney general amid concern over his surveillance policies. Paul declined to comment for this story.

Several Republicans have advised the president to stop commenting on Stone, whose sentencing for lying to Congress and witness tampering is scheduled for Thursday. Cornyn requested that Trump “steer clear” of weighing in on Stone’s sentencing and said he hoped that Barr and Trump have “reaching an understanding” after their public feud.

“The president tends to speak his mind on social media and elsewhere. In this case, I do think that Barr was correct to say that this is making my job impossible,” Cornyn said. “While the president’s free to tweet about anything else he wants, it’s really not a good idea to continue to comment on things like that.”