One of special counsel Robert Mueller’s top investigators has come under fire from conservatives.

That investigator, Andrew Weissmann, one of the team’s most prominent members, sent an email to former acting Attorney General Sally Yates praising her for not defending the Trump administration’s travel ban.

He also reportedly attended 2016 Democratic presidential nominee Hillary Clinton’s election-night party.

The investigator dubbed as special counsel Robert Mueller’s “pit bull” by The New York Times has come under fire for perceived bias against President Donald Trump.

That investigator, Andrew Weissmann, was reportedly in attendance at former Democratic presidential nominee Hillary Clinton’s election night party last year at the Jacob K. Javits Center in New York City, The Wall Street Journal reported Friday. The revelation came days after the conservative group, Judicial Watch, published an email he sent to former acting Attorney General Sally Yates praising her for refusing to defend Trump’s controversial travel ban in January.

“If it’s true that Andrew Weissmann attended Hillary’s victory party, this is getting out of hand,” tweeted Ari Fleischer, who served as White House press secretary under President George W. Bush.

Weissmann is one of the most prominent investigators on Mueller’s team. Considered to be an expert on flipping “defendants into collaborators – with either tactical brilliance or overzealousness, depending on one’s perspective,” as The Times wrote in October, Weissmann is the investigation’s “pounding heart, a bookish, legal pit bull with two Ivy League degrees, a weakness for gin martinis and classical music and a list of past enemies that includes professional killers and white-collar criminals.”

The prosecutor made a name for himself in high-profile cases involving New York’s mob bosses and at the turn of the century in the Enron scandal. He also oversaw the FBI’s predawn raid in July of former Trump campaign chairman Paul Manafort’s Virginia home.

“If there’s something to find, he’ll find it,” Katya Jestin, who used to work with Weissmann in the US attorney’s office for the Eastern District of New York, told The Times. “If there’s nothing there, he’s not going to cook something up.”

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Weissmann comes under fire

But following the revelation that one top investigator on Mueller’s team, Peter Strzok, had been reassigned from the special counsel’s team after he apparently sent anti-Trump text messages during the 2016 election, Republicans began taking aim at Weissmann as the latest example of an investigator biased against the president.

First came the email made public by Judicial Watch, where he wrote told Yates he was “so proud” and “in awe” of her decision not to defend Trump’s initial travel ban. That was soon followed up by The Journal’s revelation that he was in attendance at Clinton’s election-night party.

Foto: Andrew Weissmann. source Jeff Mitchell/Reuters

In a House Judiciary Committee hearing on Thursday, during which FBI Director Christopher Wray was testifying, Republican Rep. Steve Chabot called “the depths of this anti-Trump bias on” the special counsel’s team “absolutely shocking.”

Tom Fitton, the president of Judicial Watch, asked, “How much more evidence do we need” that the Mueller team “has been irredeemably compromised by anti-Trump partisans” after his group published Weissmann’s email.

“Shut it down,” he said.

Republican Rep. Matt Gaetz of Florida, who has been leading the charge to have the Mueller investigation shut down, told Fox News that Trump was “being persecuted by Hillary Clinton’s fan club.”

Democrats, however, said these latest attacks against the Mueller investigation, and individual investigators in particular, such as Weissmann, are just a sign of things to come with the probe reaching closer to the president.

Already, Manafort and former national security adviser Michael Flynn, two of the most prominent members of Trump’s campaign, have been charged as part of the Russia investigation. Manafort’s associate, Rick Gates, was also charged, as was early Trump campaign foreign-policy adviser George Papadopoulos.

Manafort and Gates pleaded not guilty to 12 counts including money laundering and conspiracy against the US, and Flynn pleaded guilty on December 1 to one count of making false statements to investigators about his contacts with Russians. Papadopoulos also pleaded guilty in July to lying to the FBI about his interactions with Russia-linked individuals.

“I predict that these attacks on the FBI will grow louder and more brazen as the special counsel does his work, and the walls close in around the president, and evidence of his obstruction and other misdeeds becomes more apparent,” Rep. Jerrold Nadler of New York, recently promoted to ranking member of the House Judiciary Committee, said during Thursday’s hearing.