President Trump took to Twitter Sunday to blast the FBI agent who was removed from special counsel Robert Mueller’s team after sending anti-Trump text messages to his mistress, calling his actions “Witch Hunt!” and “a really sick deal.”

Trump tweeted: “Why was the FBI’s sick loser, Peter Strzok, working on the totally discredited Mueller team of 13 Angry & Conflicted Democrats, when Strzok was giving Crooked Hillary a free pass yet telling his lover, lawyer Lisa Page, that ‘we’ll stop’ Trump from becoming President?”

The president added, “Also remember that they all worked for Slippery James Comey and that Comey is best friends with Robert Mueller. A really sick deal, isn't it?”

Through his lawyer, Strzok announced Sunday he's willing to testify before the House Judiciary Committee or any other congressional panel that invites him. The reported offer to testify came three days after Justice Department Inspector General Michael Horowitz wrote that Strzok’s messaged conversations with FBI attorney Lisa Page created the appearance that investigative decisions may have been motivated by bias against then-candidate Trump.

In the most notorious exchange, from August 2016, Strzok texted Page that “we’ll stop” Trump from becoming president.

Horowitz cited numerous exchanges between Strzok and Page, who were in a romantic relationship, but ultimately concluded that there was no evidence that anti-Trump bias played a role in the FBI’s investigation of Hillary Clinton’s private email server.

Strzok was a lead investigator on the Clinton case and later worked on the Russia investigation, but was removed from the Mueller probe last year after the Justice Department inspector general’s office brought the texts to Mueller’s attention.

Last week House Oversight Committee Chairman Gowdy, R-S.C., said findings in the IG report showed high animus.

“Once (Trump) won, (Strzok) got on the Mueller probe and wanted to impeach him,” Gowdy said on Fox News’ “Special Report.” “What a dark day it is for the FBI and for the DOJ.”