WASHINGTON — Republican Sen. Lindsey Graham said it was “at least unethical” for a Department of Justice official to be investigating Donald Trump while his wife was working for the opposition research firm that produced a controversial dossier on the then-candidate.

During an appearance on “Fox News Sunday,” the South Carolina lawmaker also called for a special counsel to be named to investigate the Justice Department and the FBI.

Graham took issue with Bruce Ohr for being involved in the Trump-Russia probe before it was turned over to special counsel Robert Mueller because his wife, Nellie Ohr, worked for Fusion GPS during the 2016 election cycle.

“Mr. Ohr should not have had any role in investigating the Trump campaign,” Graham said. “We need a special counsel to look at all things Department of Justice and FBI when it came to the Trump investigation.”

Republicans have been keen to point out any unsavory links between the Justice Department and Fusion GPS, the firm that hired former British spy Christopher Steele to produce a dossier of material on Trump’s relationship with Russia.

The dossier, which contains salacious but unsubstantiated claims about Trump, was first financed by a conservative online news site to gather information on Republican primary candidates and was taken over later by the Democratic Party and Hillary Clinton’s campaign.

Ohr was in touch with Steele and with GPS co-founder Glenn Simpson, notes, emails and text messages show.

Graham described the dossier as a “bunch of political garbage.”

“Here’s what I would tell the American people. Both campaigns were investigated by the FBI and the Department of Justice in 2016. When it came to the Clinton campaign, she got a pass. The criminal investigation of the Clinton campaign was a joke,” Graham said. “When it came to the Trump campaign, it [the investigation] was corrupt, it was biased and I think unethical.”

Graham suggested that Bruce Ohr was biased against Trump because his wife worked at Fusion GPS.

The Republican senator also pointed out how Sen. Dianne Feinstein (D-Calif.) had been told by the FBI that a person working for her had been recruited by the Chinese government to spy on her.

Trump, Graham argued, wasn’t given the same courtesy because he wasn’t warned about Russia.

“They never did the same for Trump,” Graham argued. “So these investigations against Trump were corrupt at the core.”

On Thursday, the Hill newspaper reported that House Judiciary Committee Chairman Bob Goodlatte (R-Va.) was preparing subpoenas for individuals linked to the Steele dossier, including Bruce and Nellie Ohr, as well as Simpson.