The White House and Republican lawmakers are pressing for an end to multiple investigations into the Trump campaign’s dealings with Russia, aiming to clear the president as soon as possible before the taint of scandal further damages his presidency.

President Trump expects to be publicly absolved of any wrongdoing by special counsel Robert S. Mueller III by year’s end or soon after, and several people around him say the often-impulsive president could erupt in anger if that unlikely timeline is not met.

Some associates believe, or hope, that Trump will fire his three lawyers if he is not exonerated, opening the door for a more combative approach to the Mueller investigation that he sees as an affront to his legitimacy.

Republicans leading House and Senate probes are pressing for a rapid conclusion to their own investigations of Russia’s meddling in the 2016 election. Doing so would reinforce Trump’s argument that links between his team and Russian intelligence have been over-hyped by the media and his political opponents.

“There is absolutely no collusion,” Trump told reporters Friday. “I didn’t make a phone call to Russia. I have nothing to do with Russia. Everybody knows it.”

Trump’s lawyers have repeatedly denied that Trump will try to fire Mueller, but Democrats fear the possibility and say Republicans are trying to undermine the special counsel investigation by pushing to end the congressional probes.

“Their view is that shutting down our investigation is a necessary prerequisite to shutting down Bob Mueller,” said Rep. Adam Schiff of Burbank, the top Democrat on the House Intelligence Committee.

Few outside experts believe that the Mueller probe into potential collusion with Russia and obstruction of justice will conclude by year’s end, as the White House hopes, given a recent flurry of interviews, indictments and plea agreements.

History shows such investigations, from Watergate to Whitewater, tend to linger and expand, sometimes for years. “They often took on a life on their own,” said Erwin Chemerinsky, dean of the UC Berkeley Law School.

So far, Mueller has brought criminal charges against four former Trump associates. Paul Manafort, Trump’s former campaign chairman, and Richard Gates, his deputy, were indicted on Oct. 30 on charges of fraud, conspiracy and money laundering. Both pleaded not guilty and trial is set for May. Another former campaign aide, George Papadopoulos, has pleaded guilty to lying to the FBI.

Most important, Michael T. Flynn, who briefly served as Trump’s national security advisor, has also pleaded guilty to lying to the FBI about his contacts with the Russian ambassador during the presidential transition, and he has agreed to cooperate with prosecutors. His evidence could be crucial for prosecution of others in Trump’s orbit.

White House lawyer Ty Cobb said his timeline for a speedy end to the investigation is based on “optimism and instinct” and the “character of the special counsel and his sense of duty.” Mueller’s team has not publicly shared any schedule.

"It could wrap up soon,” Cobb said in an interview. “It’s really within Mr. Mueller’s control at this stage of the game. All the White House interviews are complete.”

Another Trump lawyer, John Dowd, predicted that though Mueller may continue pursuing other individuals, “just the case for the president” will conclude by the end of the year.

Trump has told Republican lawmakers and friends recently that he is eager to see his part of the case end. If that doesn’t happen, some associates say, he could lash out.

“I suspect he’ll fire Ty Cobb,” said Sam Nunberg, a former Trump campaign advisor. “He has publicly stated that ‘It’s going to be done by X, Y and Z. We expect this.’ I don’t know how that serves your client well.”

Roger Stone, a political operative who has served as Trump’s sounding board for decades, said he expects the Mueller investigation to continue because, in his view, establishment forces in both political parties are opposed to the president.

"The president’s lawyers have not served him well by raising his expectation levels,” Stone said Thursday. “He told somebody I know as recently as yesterday that he believes he’s going to be cleared imminently.”

If Trump isn’t cleared this year, Stone added, "hopefully he will fire his lawyers and get more combative lawyers, and he’ll realize the political nature of this."

Some Republican allies in Congress seized on the Justice Department release this week of about 375 private text messages between two former members of Mueller’s team in 2015 and 2016. Some of the texts were sharply critical of Trump, calling him an “idiot” and unfit for office.

Rep. Matt Gaetz, a Florida Republican who flew with Trump to a Dec. 8 rally in Pensacola, publicly urged Trump to fire Mueller.

“Bob Mueller has recruited a team of people who are like the governing board of the 'Never Trump Movement,’” he told Fox Business News this week.

Democrats are alarmed by any attempts to short-circuit the Mueller investigation, and have spun up fears that Trump will try to get the special counsel dismissed.

“We’re on the eve of a Mueller firing,” said Rep. Eric Swalwell (D-Calif.).“The best thing Congress could do would be to cement Mueller’s role.”

Swalwell said Republicans are trying to undermine Mueller because the investigation has gained traction in Trump’s inner circle.

"This is a Hail Mary effort,” he said. “But it’s kind of the last card you play.”

Deputy Atty. Gen. Rod Rosenstein is the only official who can fire Mueller because Atty. Gen. Jeff Sessions has recused himself from the case. Rosenstein offered strong praise for Mueller on Wednesday, telling the House Judiciary Committee that he saw no reason to remove him and would resist an improper order to do so.

Trump’s attorneys have tried to tamp down such concerns even as they make the case that the investigation should be ending soon.

“Mueller will not be fired, as the White House has repeatedly and steadfastly made plain for the past five months,” Cobb said in an email.

In Congress, Democrats on the House Intelligence Committee say the Republicans who lead the panel appear intent on finishing up witness interviews as early as next week and issuing a brief report summarizing their findings by the end of the year.

Republicans have contended for months that the House probe has found no evidence of improper cooperation between the Trump campaign and Moscow, a conclusion that Democrats say is at best premature.

Carolyn Kaster / Associated Press Rep. Adam Schiff (D-Burbank), ranking member of the House Intelligence Committee, speaks to reporters after the panel interviewed Donald Trump Jr. on Dec. 6 Rep. Adam Schiff (D-Burbank), ranking member of the House Intelligence Committee, speaks to reporters after the panel interviewed Donald Trump Jr. on Dec. 6 (Carolyn Kaster / Associated Press)

If Republicans on the committee issue a report exonerating Trump, Democrats are likely to issue their own report outlining multiple contacts between Trump’s team and Russian officials, lawmakers and aides said.