President Donald Trump at a press conference during which he accused James Comey of lying under oath. Chip Somodevilla/Getty Images

President Donald Trump's lawyers are looking into whether Trump can pardon himself, family members, and aides in preparation for the outcome of the Russia investigation.

The FBI's inquiry into Russian meddling in the 2016 US election and possible collusion with the Trump campaign is being led by special counsel Robert Mueller and has so far focused on top White House aides, Trump's immediate family, and the president himself in a wide-ranging examination that has stymied the Trump administration for months.

Some of Trump's lawyers are also looking for ways to "limit or undercut" Mueller's investigation, The Washington Post reported Thursday night, citing people familiar with Trump's legal counsel's thinking.

The Trump administration has already employed such tactics to a degree by accusing Mueller and his investigative team of various conflicts of interest. Trump has pointed out, for example, that Mueller has hired investigators who openly supported Hillary Clinton, his rival in the 2016 election.

The question of whether Trump can pardon himself of any crimes has been floated before. One of Trump's advisers told The Post the president had "simply expressed a curiosity in understanding the reach of his pardoning authority."

"This is not in the context of, 'I can't wait to pardon myself,'" the adviser said, according to the newspaper.

Trump has previously floated what he suggested were conflicts of interest from Mueller as a possible reason for removing the former FBI director from the investigation.

Trump appeared to suggest as much in a Wednesday interview with The New York Times in deriding Mueller's interviewing for the FBI director job the day before he was appointed as special counsel. On Thursday, the White House walked back the president's comments, saying Trump "has no intention" to remove Mueller from the Russia investigation.

Still, the White House is said to be intent on finding fault in Mueller's investigators, The Times reported Thursday night, looking for ways to discredit the investigation or force some members of Mueller's team to recuse themselves.

Critics, including some Democrats, have described Trump's behavior toward the Russia investigators and toward the investigation itself as unbecoming of someone who is innocent.

"Russia's interference in the 2016 elections was an attack on our democracy," Sen. Mark Warner, the Democratic vice chair of the Senate Intelligence Committee, said in a statement Thursday night. He added: "The possibility that the president is considering pardons at this early stage in these ongoing investigations is extremely disturbing."

"Pardoning any individuals who may have been involved would be crossing a fundamental line," Warner said.

Eric Holder, who served as attorney general under Barack Obama, offered a warning to Trump, saying the president "cannot define or constrain" Mueller's investigation.

"If he tries to do so," Holder said, "this creates issues of constitutional and criminal dimension."