WASHINGTON (AP) - A conservative House Republican is calling on special counsel Robert Mueller to resign, citing what he says is a conflict of interest because of Mueller's relationship with fired FBI Director James Comey.

A member of the Judiciary Committee, Arizona congressman Trent Franks, describes a "close friendship" between Muller and Comey. That echoes an argument by President Donald Trump in an effort to question Mueller's credentials for the job.

Mueller is investigating Russian election meddling and possible ties to Trump's campaign.

Mueller and Comey served closely alongside each other in the Bush administration's Justice Department, and Comey has described Mueller as "one of the finest people I've ever met." But there's little evidence that they are close friends.

A spokesman for the special counsel's office is declining to comment.