WASHINGTON — President Trump accused the Justice Department on Friday of trying to frame him by planting a spy in his 2016 campaign – an allegation his own lawyer said might not be true.

Promoting a theory that is circulating in conservative circles, Trump quoted Fox Business anchor David Asman and tweeted: “Apparently the DOJ put a Spy in the Trump Campaign. This has never been done before and by any means necessary, they are out to frame Donald Trump for crimes he didn’t commit.”

But Trump lawyer Rudy Giuliani cast some doubt on that. On whether there was an “informant” in the 2016 presidential campaign, Giuliani told CNN: “I don’t know for sure, nor does the president, if there really was one,” though he said they have long been told there was “some kind of infiltration.”

Last week, the National Review raised the question of a possible FBI spy in Trump’s campaign. The article cited work by Republican Rep. Devin Nunes, an ardent Trump supporter and head of the House Intelligence Committee, who has demanded information on an FBI source in the Russia investigation.

The New York Times reported this week that at least one government informant met several times with Carter Page and George Papadopoulos, both former foreign policy advisers for Trump’s Republican campaign. The newspaper attributed the information to current and former FBI officials.

Also Friday, Giuliani said special counsel Robert Mueller has narrowed his possible interview subject areas from five to two as negotiations continue over whether the president will sit down and answer questions in the Russia investigation.