Democrats are hinging their impeachment hopes on House Democrats’ ability to dig up dirt on President Donald Trump after Special Counsel Robert Mueller’s report turned out to be a bust.

Democrat chairmen on at least four House Committees have either begun or vowed to investigate the president — the Judiciary; Oversight and Government Reform; Intelligence; and Ways and Means Committees.

The investigations ramped up just as Mueller’s report was winding down.

House Judiciary Committee Chairman Jerry Nadler (D-NY) launched a sweeping document request to 81 Trump associates on March 4 — coincidentally one day before Attorney General William Barr met with Mueller and was briefed on which way his investigation would go.

As is now widely known, Mueller did not recommend any charges related to collusion or obstruction.

We knew they wouldn’t give up. The collusion delusion fell flat, and now reports say House Democrats are preparing to “ramp up” their investigations of President Trump. Not “move on”—“ramp up.” They’re doubling down. This is a myopic obsession with politically targeting POTUS. — Mark Meadows (@RepMarkMeadows) April 23, 2019

The outcome of Democrats’ new efforts are unclear, particularly with the president indicating he will not take the fight lying down. In a recent interview, he noted he cooperated fully with Mueller’s team, but said that Congress is going too far.

“I wanted to be totally transparent. So, then we get no collusion, no obstruction,” he said on Fox News’ Hannity Thursday. “And then the House starts, ‘Now we’re going to go, and we’re going to go further.’ And I said, ‘We’ve had it. That’s enough.'”

A day before, he tweeted:

“Millions of pages of documents were given to the Mueller Angry Dems, plus I allowed everyone to testify, including W.H. counsel. I didn’t have to do this, but now they want more,” he tweeted Wednesday. “We waited for Mueller and WON, so now the Dems look to Congress as last hope!”

…..are there no “High Crimes and Misdemeanors,” there are no Crimes by me at all. All of the Crimes were committed by Crooked Hillary, the Dems, the DNC and Dirty Cops – and we caught them in the act! We waited for Mueller and WON, so now the Dems look to Congress as last hope! — Donald J. Trump (@realDonaldTrump) April 24, 2019

Hillary Clinton called on Democrats and Republicans in Congress to put politics aside and hold the president accountable in a recent op-ed. But Republicans, who have the majority in the Senate, show no sign of heeding her call.

Sen. Lindsey Graham (R-SC), one of the president’s top allies in the Senate, told CBS News’ Margaret Brennan on Sunday he did not believe the president obstructed justice even if Mueller’s report said Trump ordered White House counsel Don McGahn to fire Mueller.

“He didn’t do anything. The point is the president did not impede Mueller from doing his investigation,” Graham said, according to The Hill. “I don’t care what happened between him and Don McGahn … Here’s what I care about: Was Mueller allowed to do his job? And the answer is yes.”

Trump has vowed to fight the Democrats’ efforts to investigate him, using lawsuits, claims of executive privilege, and other means. House Democrats got a taste of what that may look like last week.

Last Monday, Trump and the Trump Organization sued House Oversight and Government Reform Committee Chairman Elijah Cummings (D-MD) to block a subpoena seeking years of financial records. Trump also sued his accounting firm Mazars USA to block it from giving records to Cummings.

On Tuesday, the White House ordered former White House personnel security director Carl Kline not to appear for a scheduled deposition with the Oversight Committee.

On the same day, the Treasury Secretary Steven Mnunchin asked Ways and Means Committee Chairman Richard Neal (D-MA) for more time to turn over six years of Trump’s tax returns and said he would give him a final decision by May 6.

On Wednesday, White House Counsel Pat Cipollone refused Cummings’ request for White House senior adviser Stephen Miller to testify before the Oversight Committee on the administration’s immigration policies, offering cabinet secretaries and other agency leaders instead, according to the Washington Post.

The White House also last week said it would fight a subpoena for McGahn. “We’re going to fight everything; we already gave them every document and witness we have,” said Rudy Giuliani, one of Trump’s attorneys, according to the Post. “Why do we have to do it again?”

While Cummings announced Sunday that Kline would come in and testify after all, the battle underscored the resistance the White House plans to put up.

Michael Caputo, a former adviser to Trump’s 2016 campaign, told the Associated Press after meeting with the president last week that he was ready to give as good as he has gotten from the Democrats.

“He’s not the least bit intimidated of all these threats of impeachment. He’s not the least bit worried about giving it as well as he’s gotten,” Caputo said. “And I think the Democrats and the media ought to strap in because it’s going to be a hell of a ride.”