WASHINGTON — White House spokesman Sean Spicer on Friday did not rule out the possibility that President Trump might invoke executive privilege to try to stop former FBI director James Comey from testifying Thursday before the Senate Intelligence Committee as part of its investigation into Russia's interference in the presidential election and possible collusion between the Trump campaign and Russian officials.

"Obviously, it's got to be reviewed," Spicer said in response to a reporter's question about executive privilege. "My understanding is the date for that hearing was just set. I haven't spoken to counsel yet. I don't know how they're going to respond."

Earlier Friday, Kellyanne Conway, counselor to the president, said on ABC's Good Morning America that "the president will make that decision."

"When Director Comey goes to testify, I think that will be a very clarifying moment," she said. "It's more important to have somebody testify under oath, frankly, than to have his friends and his former colleagues out there speaking to the media, not under oath."

Comey's much-anticipated testimony is expected to focus on his conversations with Trump, including about allegations that the president asked Comey to back off the FBI's investigation of former national security adviser Michael Flynn. Trump abruptly fired Comey on May 9 as Comey was leading that investigation.

Trump fired Flynn in February amid questions about whether he inappropriately talked about U.S. sanctions against Russia with a Russian official and then misled Vice President Pence about it. Both the House and Senate Intelligence committees have issued subpoenas for Flynn's testimony and documents from his businesses.

Executive privilege is a legal doctrine that allows a president to withhold information from other branches of government — in this case, Congress. If Trump does invoke it, his action would likely be challenged in court. It also could harm the president politically by making it look like he has something to hide.

Some legal experts and members of Congress have said that it may be difficult for Trump to invoke executive privilege in regard to his conversations with Comey because the president has talked publicly about those conversations and about why he fired Comey.

In 1974, during the Watergate scandal, the U.S. Supreme Court ruled in U.S. v. Nixon that executive privilege can only be invoked in certain circumstances, such as when a president is trying to protect national security.