Publicly trashing former FBI Director James Comey while he's a witness is an obstruction of justice case was a big mistake for Sarah Huckabee Sanders.

White House press secretary Sarah Huckabee Sanders may be the next administration official who needs to lawyer up as Robert Mueller’s special counsel investigation accelerates.

Specifically, Sanders may have placed herself in legal jeopardy by agreeing to be the White House point person for the nasty smear campaign it’s been running against former FBI Director James Comey, according to Sen. Sheldon Whitehouse (D-RI), who appeared on MSNBC’s “Hardball” Monday night with Chris Matthews.

Mueller’s legal team is currently investigating whether Donald Trump is guilty of obstruction of justice for firing Comey in May while the FBI was investigating Trump’s ties to Russia during last year’s campaign.

At the time, Trump openly admitted he removed Comey because he didn’t like the way the Russia probe was going. So Comey remains a crucial witness to that case. And he remains a crucial witness that Sanders has tried to publicly tarnish.

“If the motivation was to poison the reputation of James Comey with the grand jurors, you’ve got another count in the indictment,” said Whitehouse, who previously served as Rhode Island’s attorney general and served as U.S. attorney for the state in the 1990s. Whitehouse cited a code from federal obstruction of justice statute that forbids any attempt to influence grand jurors.

WHITEHOUSE: The three torpedoes that Sarah Huckabee’s Sanders shot at James Comey, which open up an entirely new avenue in the case for Mueller. There’s a statute, 1504 in the obstruction of justice statutes, that talks about attempts to influence grand jurors. So the question for Sarah Huckabee Sanders is, “Who asked you to do that? Who told you to do that?”

And once you know who it is, you look to their motivation. And if their motivation was to poison the reputation of Jim Comey with grand jurors, you’ve got another count in the indictment.

Whitehouse made his comments the same day news broke that investigators from Mueller’s office reportedly told Trump’s former campaign manager, Paul Manafort, that he should expect to be indicted. The federal government wiretapped Manafort both before and after the 2016 election, CNN reported Monday and captured conversation between him and Trump.

In terms of context and how bizarre it is to have a White House try to smear a witness in a criminal case that targets the White House, imagine if during the Bill Clinton impeachment imbroglio, the White House press secretary, during official briefings and behind the White House podium, regularly attacked Monica Lewinsky and suggested she be the subject of a criminal investigation.

Note that Clinton White House aide Sidney Blumenthal became enmeshed in a long-running impeachment-era controversy because he was accused of disparaging Lewinsky in a single private conversation after the scandal story broke. At the time, the allegation was treated as scandalous. (Blumenthal denied the charge.)

Yet today, the White House press secretary openly tries to undermine Comey’s credibility while he remains at the center of a federal investigation into possible obstruction of justice by Trump and his team.

That’s why Whitehouse thinks Sanders is heading for legal trouble.