By David Morgan and Jonathan Landay
WASHINGTON (Reuters) - U.S. Senate Democrats are considering legal action over President Donald Trump's appointment of a new acting attorney general, congressional sources said on Friday, as some outside experts called Trump's move unconstitutional.
Trump on Wednesday named Matthew Whitaker to replace former Attorney General Jeff Sessions, who was forced out after months of being attacked by Trump for recusing himself from an ongoing probe of Russian meddling in the 2016 presidential election.
The move made Whitaker supervisor of the investigation, which has hung over Trump's presidency. Whitaker has criticized the probe in the past as too wide-ranging, a view that raised concerns among Democrats that Sessions' ouster and Whitaker's appointment might be a precursor to Trump moving to end it.
Senate Democrats were pondering suing Trump, the sources said, on the grounds that, in naming Whitaker, the president ignored a statutory line of succession at the Justice Department and deprived senators of their constitutional "advice and consent" role on some presidential appointments.
"The only two paths to that office are regular succession, and advice (and) consent," said a source close to the Senate Judiciary Committee.
The Appointments Clause of the U.S. Constitution states that some senior government officials, known as "principal officers," must be confirmed by the Senate.
Democrats, as the minority party in the Senate, might need some Republican support to have legal standing to sue Trump under the Appointments Clause, said Andrew Wright, who was a White House lawyer under former President Barack Obama.
The source close to the Senate Judiciary Committee said that Democrats were unsure whether they would reach out to Republicans to join the lawsuit, but said such a move was "not likely."
Senate Democratic leader Chuck Schumer said on Friday that Deputy Attorney General Rod Rosenstein, a career Justice Department official already confirmed by the Senate, should have been named the new attorney general after Sessions was removed.
"You ignored the statutory line of succession," Schumer said in a Nov. 9 letter to Trump. "The appointment of Mr. Whitaker is further clouded by unresolved constitutional questions about the legality of such an action."
John Yoo, a former Justice Department lawyer in the George W. Bush administration, said "the Supreme Court made clear that the Attorney General is a principal officer," in a 1998 case.
"Therefore, Whitaker cannot serve as acting Attorney General ... Any other officer in the Justice Department who was appointed through advice and consent can serve, including the Deputy AG, the solicitor general, and the assistant AGs," said Yoo, now a law professor at the University of California, Berkeley.
Trump's ouster of Sessions and appointment of Whitaker triggered concerns among lawmakers that the president planned to undermine Special Counsel Robert Mueller's 18-month probe into Russian meddling in the 2016 election and any collusion between Moscow and Trump's campaign.
Republican Senator Susan Collins said in a statement on Friday that Mueller must be allowed to complete his investigation. "I am concerned about comments that Acting Attorney General Matthew Whitaker has made regarding the Special Counsel and the parameters of his investigation," she said.
"We should bring to the Senate floor legislation that would put restrictions on the ability of President Donald Trump to fire the Special Counsel," she added.
Trump said on Friday, as he was departing Washington for a trip to Paris, that he had not discussed the Mueller probe with Whitaker before appointing him, and it was up to Whitaker whether he wanted to be involved with the investigation.
Speaking to reporters at the White House, Trump defended his choice of Whitaker, saying the former U.S. attorney for the southern district of Iowa had an excellent reputation and came highly recommended by former Iowa Governor Terry Branstad, who is now Trump's ambassador to China.
At the same time, Trump repeatedly emphasized in his remarks to reporters that he did not know Whitaker, whom he tapped to replace Sessions on a temporary basis.
"Matt Whitaker - I don’t know Matt Whitaker," Trump said.
A Justice Department spokeswoman has said Whitaker would oversee all matters under the department's jurisdiction, including the Mueller investigation.
Democrats have called on Whitaker to recuse himself.
Trump said, "No matter who I put in, they go after him ... He's a highly respected man, especially by law enforcement, and I think he's going to do a great job."
U.S. intelligence agencies have said Russia interfered in the 2016 election in an attempt to tip it towards Trump and away from his Democratic opponent, former Secretary of State Hillary Clinton.
Russia has denied interfering, and Trump has repeatedly said there was no collusion between his campaign and Moscow, slamming the Mueller probe as a "witch hunt."
"I didn’t speak to Matt Whitaker about it," Trump said of the probe, adding he did not rule out sitting down for an interview with Mueller. "I haven't ruled out anything," he said. "I haven't even thought about it."
(Reporting by David Morgan and Jonathan Landay; Additional reporting by Roberta Rampton, Jan Wolfe, Susan Cornwell, Amanda Becker and Susan Heavey; Editing by Kevin Drawbaugh and Paul Simao)