Senate Democrats are exploring the idea of suing the Trump administration over Matthew Whitaker’s appointment as acting attorney general, several Democratic lawmakers confirmed on Friday.

The suit would seek to invalidate Whitaker’s appointment, by arguing that it was an unconstitutional violation of the Senate’s “advise and consent” powers. If successful, it would force Trump to either formally nominate a replacement for former Attorney General Jeff Session or elevate, on an acting basis, someone from within the department who had already received Senate confirmation.

“We have been doing a deep dive on potential causes of action concerning the constitutional issues raised by the Whitaker appointment and also obvious obstacles that could be raised to any court initiative, not the least of them standing," Sen. Richard Blumenthal (D-CT) told The Daily Beast. "We’ve been through a few of these issues in my emoluments lawsuit, principally the standing one. So we’re looking at the array of legal flaws in the appointment and considering which of them are challengeable in court.”

A spokesperson for the Justice Department declined to comment as no suit has yet been filed.

Talks of initiating a lawsuit have been limited as numerous lawmakers remain out of town. A separate lawmaker said he had not heard of discussions but would not be surprised if Senators did explore making a constitutional challenge to the Whitaker appointment.

Blumenthal, speaking for himself and not for others, said that it’s not entirely clear such a challenge could work. A plaintiff must have standing (i.e., prove that he or she has been harmed) in order to bring a suit in the first place.

Though a senator could argue that the harm of Whitaker’s appointment was that it deprived Congress of its constitutional duty, legal scholars are not convinced that this would pass judicial muster. A better foundation for standing would be for the plaintiff to have been directly affected by one of Whitaker’s first orders or memorandums, they say.

Stephen Gillers, a law professor at NYU, told The Daily Beast that such a suit could potentially succeed.

“The Senate and each senator has obvious standing to challenge the Whitaker appointment,” he said. “It’s not clear as of now who else will or can. The Senate’s standing is based on the fact that the appointment bypasses, for up to 210 days or longer, its advise and consent power. Of course, only the Democrats would be interested in the legal action but any senator has standing. It is the Senate that is most immediately harmed through the appointment.”

That isn’t a consensus view, though.

“It’s a ridiculous lawsuit,” Cleta Mitchell, a conservative lawyer with Foley & Lardner LLP, said of the idea. “The president can appoint who he wants to. But you know that doesn’t keep them from going to some crazy 9th circuit judge, an Obama-appointee in California, and getting something––but I don’t think that they’ll get anywhere with that.”

“The Senate Democrats are just trying to make themselves relevant after their shellacking on Tuesday,” she added.

Whitaker was appointed the nation’s top law enforcement officer under the Vacancies Reform Act, which allows for the filling of vacant positions up to, in certain cases, 210 days. But because he was made a “principal” officer—in that he reports directly to the president—his ascension has been legally dubious. On Thursday, two constitutional lawyers, Neal Katyal and George Conway, argued that the appointment was unconstitutional precisely because Whitaker had not been confirmed by the Senate for the AG job or the job had held prior, chief of staff to the AG. Whitaker had been confirmed by the Senate in 2004 as a U.S. Attorney in Iowa. But Katyal and Conway said that confirmation had effectively lapsed and was irrelevant to the current posting.

On Friday, Senate Minority Leader Chuck Schumer (D-NY) sent a letter to President Donald Trump questioning his “authority to make” the Whitaker appointment. “I see no legitimate reason for you to have taken the unprecedented step of naming Mr. Whitaker,” Schumer wrote. “As an unconfirmed political appointee, Mr. Whitaker has not been subject to the scrutiny that the Constitution requires to ensure that he has the character, integrity and ability to fulfill the grave responsibilities of this job.”

Schumer’s office declined to comment on the possibility of a lawsuit accompanying the letter.

David Rivkin, a constitutional attorney for Baker Hostetler who served in the Ronald Reagan and George H. W. Bush administrations, said the Senate would have to vote as a body to have institutional standing to sue over Whitaker’s appointment––like the House did when it sued over the Affordable Care Act.

“The case law is absolutely clear: A rump group of senators can never have standing to vindicate institutional authority that they claim is being infringed because it’s not theirs to vindicate, any more than if a corporation or an association sues in federal court, it cannot be done by a janitor or a third assistant to a fifth deputy,” he said.

Beyond the legality of his appointment, Whitaker has drawn criticism for comments he made on Justice Department officials as a Trump-boosting pundit. Whitaker made frequent cable news and radio appearances during Trump administration, lambasting Special Counsel Robert Mueller’s investigation into potential coordination between Trump associates and the Russian government. As The Daily Beast first reported, he said last summer that there was “no collusion with the Russians and the Trump campaign.” He also defended a conversation that Trump ally Gen. Michael Flynn had with Russian ambassador Sergei Kislyak during the transition period. Flynn later lied about the conversation, and ultimately pleaded guilty to lying to the FBI. He is awaiting sentencing. Whitaker has also accused Mueller of leaking to reporters.