Donald Trump. Ilia Yefimovich/Getty Images The chief ethics lawyer for former President George W. Bush was troubled by The Washington Post's Monday report that President Donald Trump asked two of the top US intelligence officials in March to push back against an FBI investigation into whether his campaign colluded with Russian officials in the 2016 presidential election.

"I'm concerned about it," Richard Painter, who served as Bush's top ethics lawyer from 2005 to 2007 and is currently a law professor at the University of Minnesota, told Business Insider. "You just have more of the same. I mean, this is obstruction of justice. This investigation needs to go forward and it involves the president's campaign. He should stay out of it.

"This is the mistake that Nixon made," he continued.

Painter was referencing former President Richard Nixon, who resigned from office after he attempted to interfere in an FBI investigation into the Watergate break-in and subsequent scandal.

"Because Nixon never ordered anyone to break into the Watergate," Painter said. "He just should've let it be and not gotten involved and had the White House stay out and let the prosecutors find the people who ordered the break in and prosecute them."

"And you'd have mid-level people and that'd be the end of the discussion," he continued. "But Nixon decided he's going to do a cover-up and try and stop the investigation. And that blew up in his face. And that's unfortunately where Trump is going right now."

It remains a mystery as to whether Nixon did or did not order the break-in, but there was not a smoking gun that showed he did.

So far, the US government and intelligence agencies have not produced any evidence that the Trump campaign did indeed collude with Russian officials. Investigations are ongoing.

The Post, sourcing current and former US officials, reported Monday that Trump appealed to both Director of National Intelligence Dan Coats and National Security Agency Director Mike Rogers to publicly deny there was any collusion between his camp and Russia during the election, but both refused to do so. Trump made the request after FBI Director James Comey announced the existence of the FBI's investigation at a March hearing before the House Intelligence Committee.

Comey, who was controversially fired by Trump earlier this month, was overseeing that investigation.

"The White House does not confirm or deny unsubstantiated claims based on illegal leaks from anonymous individuals," an unnamed White House spokesman told the Post. "The president will continue to focus on his agenda that he was elected to pursue by the American people."

During a hearing before the Senate Armed Services Committee on Tuesday, Coats said it was "not appropriate" for him "to comment on any of that" when asked about the content of the Post's report, neither confirming nor denying it.

The Post reported that other senior White House officials also discussed how to push Comey to drop a probe into Trump's former national security adviser, Michael Flynn, and his ties to foreign governments.

James Comey. Eric Thayer/Getty Images

That story came at the tail end of what's been nearly two weeks of fallout from Trump's firing of Comey.

In the days after Comey's firing, reports surfaced that Trump had asked Comey to take a loyalty pledge and later suggested that he "let go" of the investigation into Flynn. Trump has disputed these accounts, but that legal experts have said that if they're true, Trump's actions could amount to obstruction of justice.

Deputy Attorney General Rod Rosenstein then appointed former FBI Director Robert Mueller to oversee the Russia investigation. Days later, The New York Times reported that Trump told Russian diplomats in an Oval Office meeting that his firing of Comey, whom he called a "nut job," had taken "great pressure" off him with regard to Russia.

Painter said the entire episode has been confusing because Trump "doesn't need to do that." He said he doubts that Trump collaborated with Russia, though people working for him might have.

"It's silly for the president to do this and try to defend Flynn," he continued. "I mean Flynn was a liar. Flynn lied. Why defend Flynn? Well he's worried that Flynn might turn evidence on other people. Well, if his campaign managers were doing stuff with the Russians then they get in trouble. But he could stay away from that. He's not making smart decisions here."

He said that the Post's story, if true, is just the latest piece in what's becoming the "piling up" of "evidence of obstruction of justice."

"That's what got Nixon," he said. "It was the cover up."