What is witness tampering, and could Trump possibly be charged?

The House select committee investigating Jan. 6 is holding its second prime-time hearing on Thursday, which will focus on the Trump White House's reaction to the insurrection as it unfolded.

Following a recent and highly publicized hearing, renewed attention is on witness tampering and the possibility that it was committed by Trump.

During a recent hearing, Wyoming Republican Rep. Liz Cheney, the committee's vice chair, said that Trump attempted to call a witness in the committee's investigation into last year's attack on the U.S. Capitol.

"After our last hearing, President Trump tried to call a witness in our investigation -- a witness you have not yet seen in these hearings. That person declined to answer or respond to President Trump's call and, instead, alerted their lawyer to the call," Cheney said at the time.

The committee warned against witness tampering as it continues its investigation. "Let me say one more time, we will take any effort to influence witness testimony very seriously," Cheney said.

But what is witness tampering, and did Trump possibly commit it?

What is witness tampering?

Witness tampering is a federal crime and is considered a form of obstruction of justice.

According to the Department of Justice, witness tampering occurs when someone tries to "influence, delay or prevent the testimony of any person in an official proceeding."

"It's either threatening a witness with some type of harm if the person doesn't testify in a certain way or doing this thing, which is defined by Congress as corruptly persuading someone to say something," Robert Weisberg, faculty co-director of the Stanford Criminal Justice Center, told ABC News. "Unfortunately, Congress has done an absolute horrible job defining the crime."

Congress has the authority to investigate if a crime took place, but it doesn't have the power to charge someone with witness tampering -- that is left up to the Department of Justice.

A person could be sentenced to up to 20 years in prison if found guilty of witness tampering.

Donald Trump's alleged witness tampering

The committee has examined not only the insurrection at the Capitol, but also then-President Trump's possible role in the events leading up to, during and after that day, actions the committee says were a "dereliction of duty" on his part.

Trump, who has denied any wrongdoing, has repeatedly criticized the House select committee for its investigation into the Jan. 6 riot, calling it one-sided and politically motivated.

Cheney's bombshell accusation about Trump raises questions on if he committed a crime and, if so, if there's enough evidence to charge him.

"It would depend on the strength of the case," Peter Zeidenberg, a former federal prosecutor, told ABC News. "When people make calls like that, usually it's a little more guarded and a little bit of a wink wink, nudge nudge."

Trump allegedly attempted to call a White House support staffer, a person he wouldn't normally call, sources said.

Despite not reaching the witness during the purported call, a crime still allegedly took place, this according to guidance from the DOJ under section 18 U.S.C. 1512, "Protection of government processes -- Tampering with victims, witnesses or informants."

"There is no requirement that the defendant's actions have the intended obstructive effect," it reads.

Trump spokesperson Taylor Budowich sharply criticized Cheney's accusation while also going after the media -- but did not deny her claims.

"The media has become pawns of the Unselect Committee. Liz Cheney continues to traffic in innuendos and lies that go unchallenged, unconfirmed, but repeated as fact because the narrative is more important than the truth," he tweeted on July 12.

Cheney's claim against the former president isn't the first time Trump has been accused of obstructing justice.

Michael Cohen

Michael Cohen, Trump's longtime personal lawyer, was convicted in 2018 for tax evasion, violating campaign finance rules and lying to Congress.

For years, Cohen had signaled loyalty to Trump. But after the FBI raided his home in 2018, he was open to cooperating with special counsel Robert Mueller's investigation into the then-president.

Cohen's lawyer said that Trump's advisers were hinting that he would pardon Cohen following the FBI's raid into his home. Once Cohen agreed to testify, Trump began publicly attacking his former lawyer and suggested that his father-in-law should be investigated.

The House Committee on Oversight and Reform said at the time that "efforts to intimidate witnesses, scare their family members, or prevent them from testifying before Congress are textbook mob tactics that we condemn in the strongest terms. Our nation's laws prohibit efforts to discourage, intimidate, or otherwise pressure a witness not to provide testimony to Congress."

In 2019, after a delay, Cohen testified in front of the House Oversight Committee about his time working for his former boss. Cohen said he initially delayed his testimony because of "ongoing threats against his family from President Trump."

Could Trump be charged?

It's unlikely Attorney General Merrick Garland will charge Trump, especially if he plans to run for president again, according to Weisberg.

"If he declares he's running for president, even though that doesn't give him any immunity from indictment, we know that's exactly the situation Garland fears, namely indicting someone amidst a presidential campaign, because he doesn't want the criminal justice systems to distort the political process," Weisberg said.

"There's a weird kind of leverage that Trump has here," he added.