President Donald Trump on Thursday tapped David Kautter, a senior tax official at the Treasury Department, to become acting IRS commissioner, starting Nov. 13.

Kautter will temporarily take over the top job at a critical time for the agency, as Republicans work on a major tax code overhaul and an IRS audit of the president’s own taxes continues. He will succeed Commissioner John Koskinen, the embattled IRS chief whose term ends Nov. 12.

If a landmark GOP tax bill passes before the end of the year, as top Republicans intend, Kautter would have the monumental task of implementing the first major changes to the tax code in decades — with tax-filing season looming.

Overseeing the audit of Trump’s tax filings could also be an awkward scenario for Kautter, twice tapped for administration jobs by the president. Those challenges are on top of the usual headaches that come with leading the IRS, namely overseeing an unpopular agency under a perpetual budget crunch.

Kautter, previously a Senate aide and tax consultant, was confirmed by voice vote on Aug. 3 as assistant secretary for tax policy at Treasury. Former Treasury officials and observers predicted then that Kautter would serve as a sort of mediator between political appointees and career staffers at Treasury, as well as a bridge to Congress and a tax policy “whisperer” within the administration.

Republicans on the Hill had positive reactions Thursday to the designation, but they were more focused on lambasting the outgoing commissioner.

“I think it’s good to get a fresh start at the IRS,” said House Ways and Means Chairman Kevin Brady. “It is long past overdue that they really open their books so that we understand exactly the challenges [of] that agency and the mess that they’re in. They are really good people; they have really poor leadership.”

Koskinen, a 2013 appointee of President Barack Obama, was loathed by conservative Republicans in Congress who sought to impeach the IRS chief and earlier this year asked Trump to fire him.

Rep. Mark Walker of North Carolina, chairman of the conservative Republican Study Committee, released a blistering statement about Koskinen after the White House announced Kautter’s designation.

“It’s a failure of government that IRS Commissioner John Koskinen will be able to serve his full tenure after consistently abusing the public trust, lying to Congress, and obstructing investigations,” Walker said. “I can only hope that as he leaves the IRS building, his head is not held high and that he will be remembered as empowering the agency’s extensive actions of political abuse.”

Walker added that he looks forward to “working with the administration and meeting with Mr. Kautter as soon as possible to discuss his plans to fix the IRS.”

Brady said having someone new heading the agency could also help implementation of a tax code overhaul, “especially since a major plank of tax reform, which will follow next year, is redesigning the entire IRS from top to bottom and turning it into a customer service-oriented organization for a much smaller, fairer tax code.”

Treasury Secretary Steven Mnuchin said Kautter will continue to do the job of assistant Treasury secretary for tax policy even while filling in at the IRS until a permanent commissioner is named and confirmed.

“David will provide important leadership while we wait to confirm a permanent commissioner,” Mnuchin said in a statement. “Assistant Secretary Kautter has had an illustrious 40-year career in tax policy, and I am confident that the IRS and the American people will benefit from his experience and insight.”

Kirsten Wielobob and Jeff Tribiano, deputy commissioners at IRS, will continue to manage daily operations at the agency under Kautter, Mnuchin said.

Lindsey McPherson contributed to this report.