It’s been a “tough week” and “rough patch for Mick Mulvaney” that has not aided his credibility, said Senate Majority Whip John Thune (R-S.D.) bluntly.

“It’s hard to figure out what led him to make some of those statements last week, both in the initial news conference and then the follow-up. I’m glad they walked some of that stuff back but yeah, it’s hard to explain,” Thune said in an interview. “He’s trying to make amends and correct the record, so to speak, so we’ll see. Ultimately, he serves at the pleasure of the president.”

And if Trump is weighing whether to keep Mulvaney or cut loose the third man who’s held the seemingly impossible job, many Senate Republicans are not likely to offer the embattled aide much support. Trump himself did not answer a question about Mulvaney’s status on Monday and the White House did not return a request for comment for this story.

The former conservative congressman from South Carolina has never been a favorite of the congressional establishment. He was a Freedom Caucus member agitating against the GOP speaker, received no Democratic votes for his confirmation to be Trump’s White House budget chief and was sidelined during budget discussions earlier this year with Hill leaders.

Senate Republicans are currently threatening to torpedo the judicial nomination of his close friend Sul Ozerden, an episode further testing the limits of Mulvaney's sway on Capitol Hill.

One Senate Republican noted that “acting” has remained next to Mulvaney’s name for nearly a year “and there’s a reason for that.”

“He’s always been on the edge,” this senator said. But now “he’s on thinner ice” than ever.

Sen. Josh Hawley (R-Mo.), a close ally of the president who opposes Ozerden, said he was shocked when he heard Mulvaney say aid to Ukraine was frozen as Trump sought an investigation into Democrats, before spending the next 72 hours trying to walk it all back.

“I thought: Whoa. This is new,” said Hawley, adding that Mulvaney’s later explanations satisfied him.

“It seems starkly at odds with what the president had been saying and what others in the administration had been saying,” Hawley said of Mulvaney’s initial comments. “I don’t think it’s helpful. It’s certainly a distraction. … It’s certainly introduced a lot of static.”

In the Trump era, the job of chief of staff has not necessarily involved working closely with congressional leaders.

Senate Majority Leader Mitch McConnell prefers to speak to the president himself rather than Mulvaney, according to a source familiar with the dynamics; the source added that McConnell has always gone to the president directly regardless of who is chief of staff.

And under Mulvaney, Trump’s open-door policy with rank-and-file Republicans has become even more freewheeling than usual. Senators speak to the president frequently with no layering of staff, allowing access to a president for whom no one else can really speak.

That’s been a boon to some senators, like Sen. Rand Paul (R-Ky.), who has seen Trump move his way significantly on foreign policy as the president prepares to pull most or all of the U.S. presence out of Syria. Paul said on Monday that Mulvaney is doing a “great job.”

Mulvaney has also pleased Paul but frustrated many other Republicans by advancing budget cutting priorities. He’s done more media briefings than the White House press secretary, though his credibility has taken some hits, like when he strenuously objected to a POLITICO story saying he was advocating to get rid of Labor Secretary Alex Acosta; three days later Acosta was gone.

Over the past week, Mulvaney has found himself in increasingly dire straits at precisely the wrong time. GOP lawmakers were already exhausted from answering questions about the president’s decision to abruptly withdraw from northern Syria and whether it’s appropriate to request political assistance from a foreign government.

Then came Mulvaney with two new controversies.

During a White House briefing Thursday, Mulvaney appeared to acknowledge a long-denied quid pro quo with Ukraine. And he said the G-7 would be held at Trump’s property in Doral, Fla., setting off a new wave of alarm that Trump was profiting off the presidency and violating the Constitution.

The acting chief of staff has been engaged in clean-up duty since, hosting some congressional Republicans at Camp David on Saturday. The president himself dropped the Doral gambit after sustained criticism from Democrats and a handful of members of his own party.

“We found him to be between a rock and a hard place, and it’s been one of those things where he fully intended a different message than the one that came out and he’s doing his best to correct any misperceptions,” said Sen. Mike Rounds (R-S.D.).

Yet correcting the record has proved difficult, with Rep. Francis Rooney (R-Fla.) likening Mulvaney’s initial walk-back to trying to use an “Etch A Sketch.” The following days brought more confusion.

"He’s never asked me for any advice, and I don’t expect him to ask me for advice on this."

Mulvaney said Sunday that the United States withheld foreign aid to Ukraine because of Ukrainian corruption and concern about whether European countries were also providing assistance. But Fox News host Chris Wallace noted that Mulvaney left out a third reason he mentioned in his Thursday news conference — that aid was conditioned upon Ukrainian cooperation with a Department of Justice investigation. DOJ, meanwhile, has said it is conducting no such probe.

Still, the performance was preferable to Thursday’s off-the-cuff affair, during which Mulvaney, asked directly about a “quid pro quo” between aid to Ukraine and probing the 2016 election, said the U.S. withholds aid under similar conditions “all the time” and that people should “get over it.”

“Obviously what [Mulvaney] said in the press conference was a real concern because he said, in effect, they were holding up funding going to Ukraine in part based upon a desire to have Ukraine carry out an investigation with regards to the 2016 election,” Sen. Mitt Romney (R-Utah) told reporters on Monday.

“I guess I liked the Sunday explanation better than the earlier one,” said Sen. Roy Blunt of Missouri, the No. 4 GOP leader. Asked whether Mulvaney should continue speaking about Ukraine, Blunt replied icily: “He’s never asked me for any advice, and I don’t expect him to ask me for advice on this.”

Despite the limp defense for Mulvaney, no senators were openly advocating Mulvaney’s dismissal, in part because there’s no obvious successor.

Sen. Susan Collins (R-Maine), who more willingly criticizes the Trump administration than most, left it up to the president. Sen. Lindsey Graham (R-S.C.) said Mulvaney is in a familiar place for any politician at the highest rungs of power.

“We’ve all been in that barrel at one point in our political lives,” Graham said.