Rudy Giuliani, one of President Trump’s lawyers, lambasted special counsel Robert Mueller’s probe, calling it the “most corrupt investigation” he’s ever seen.

“This is the most corrupt investigation I have ever seen that the Justice Department is allowing to go forward,” Giuliani told ABC News on Sunday. “I’ve never seen an investigation with texts from FBI agents, now seven of them, that have such extraordinary bias.”

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The former New York City mayor was referencing messages exchanged by FBI employees that were hostile to Trump. The messages were revealed in a report from the Justice Department's inspector general last month.

Giuliani also criticized the members of Mueller's team, saying the special counsel has “very, very severe partisans” working on the investigation into Russian meddling and possible collusion between the Trump campaign and Russia. He said “biases” should be explored surrounding Mueller’s probe.

“How you could end up hiring a group of people that are as prejudiced and biased as this group, in their record at least, is extraordinary,” he said. “And how you could expect us to just walk our client up like a lamb going to the slaughter? We wouldn’t be lawyers.”

Giuliani said Trump’s legal team is “close to determining” whether the president will sit down for an in-person interview with Mueller and said Trump “wants to testify.”

Trump frequently criticizes Mueller’s investigation, calling it a “witch hunt” that is run by “ 13 angry Democrats.” Mueller himself is a lifelong Republican.