WASHINGTON — A White House already sidetracked by special counsel Robert Mueller's probe is now racing to prepare for a new Congress that is vowing more aggressive oversight of the administration. Belatedly, the White House has begun to fill key positions to face off with Democrats in a second front of legal sparring.

Democrats take control of the House of Representatives in just 17 days and are already preparing a multi-pronged oversight strategy. But White House preparations stand in contrast to how the Obama administration girded for the incoming GOP Congress it faced after its first two years in office — in part because a new legal team is just getting started, two Republican sources tell NBC News.

Leading the administration into at least two years of legal trench warfare with Democrats will be White House counsel Pat Cipollone, who started the job formally last week after a longer-than-anticipated security clearance review. Trump tapped Cipollone, a prominent GOP attorney and former Justice Department official, in early October to replace Don McGahn as the White House’s top lawyer.

Among his first challenges is to quickly fill other vacancies in the office that followed McGahn’s departure.

Forming the core of the new White House counsel team are four deputies, according to a source with direct knowledge. All are described as well-respected former Justice Department lawyers.

Mike Purpura, a former federal prosecutor and Justice Department official, is the deputy White House counsel leading the response to congressional investigations, according to a source familiar with the process.

The other deputies include Pat Philbin, who served in the George W. Bush Justice Department; Kate Comerford Todd, a former head of the litigation arm of the U.S. Chamber of Commerce; and John Eisenberg, who is remaining in his position having served under McGahn.

In the weeks and months before Republicans formally took control of the House in the 2010 midterms, representatives from President Obama's White House counsel’s office and communications shop launched a series of meetings with every Cabinet department to plan ahead.

The discussions involved identifying likely topics of interest from the GOP and what sorts of information they might target in subpoenas. Dedicated teams were set up inside the White House and at the agencies with best practices in mind for how to responding when the requests came in.

Even before the elections, a process had been set up within the Obama White House to anticipate and respond to potential political land mines. But it escalated after the election, particularly at the Justice Department, where officials knew they were going to be facing a range of GOP inquiries, but also because the department plays a key role in helping to litigate any impasse over subpoenas.

A source familiar with the Trump administration says it expects a “knock-down, drag-out fight” in the face of expected congressional subpoenas, which could play out in three ways: mounting court challenges, claiming executive privilege, or negotiating.

The job of negotiating would fall to the White House Office of Legislative Affairs, which got a new director, Shahira Knight, this summer. The White House communications staff would typically take the lead role in messaging, but that already-depleted staff is besieged by responding to a stream of daily controversies. And two Republican sources say the White House isn’t yet prepared for the task of defending the administration since the counsel’s team is just getting started.

Trump has adopted a term first coined by Senate Majority Leader Mitch McConnell to warn Democrats against aggressive oversight, calling it “presidential harassment.” Weeks after the midterm election he said the prospect of Capitol Hill investigations was to blame for a stock market downturn.

The prospect of Presidential Harassment by the Dems is causing the Stock Market big headaches! — Donald J. Trump (@realDonaldTrump) November 12, 2018

Matthew Miller, a former Justice Department spokesperson in the Obama administration and now an NBC News contributor, noted that in multiple battles with the Republican House the Obama administration only once invoked executive privilege as reason for not complying with a House subpoena, related to its probe of the botched gun-running operation known as Fast and Furious. But fights over executive privilege are something many past administrations have waged.

“The Trump administration will probably aggressively argue privilege in a way that previous administrations have,” he said. “If they are willing to take the political heat, which my guess is they will, they can just avoid turning over things that are covered by somewhat murky privileges. The bigger question is, do they just completely flaunt subpoenas in a way that previous administrations haven’t?”