Rep. Eric Swalwell, a 2020 Democratic presidential underdog, reacted to Attorney General William Barr's Thursday morning remarks on the Mueller report by calling for his immediate resignation, claiming that the investigation had been "tainted."

“He came to this job already biased. Today, he made a show of allegiance to the President over the American people by declaring ‘no collusion’ and excusing the President on the basis of his emotional state," the California congressman said in a press release. "He has proved that he’s an embedded Trump ally who puts this President’s political future above of the rule of law. That makes him unfit to serve. He must resign.”

Swalwell said that special counsel Robert Mueller's redacted report "suggests the President obstructed justice, but Barr excused him." The press release did not address Mueller's assessment that President Trump did not collude with the Russian government.

Barr had summarized the findings of the Mueller report in a press conference earlier Thursday. Regarding the 10 instances identified by Mueller as potential obstruction, Barr said that Trump was not seeking to obstruct but rather was "frustrated and angered by a sincere belief that the investigation was undermining his presidency, propelled by his political opponents, and fueled by illegal leaks."

Swalwell, who has been an aggressive critic of Trump's relationship with Russia, appeared to be the first 2020 presidential candidate to call for Barr's resignation. Other Democratic presidential candidates, such as Sen. Kamala Harris of California, decried Barr's "spin" on the report.

Swalwell announced his bid for the White House on April 8 during an episode of "The Late Show with Stephen Colbert."

“I’ve been in Congress for six years, I’ve defended our country from the Intelligence Committee while democracy has been on the ropes ... and I see a country in quicksand, unable to solve problems and threats from abroad, unable to make life better for people here at home. Nothing gets done,” he told Colbert.

A Morning Consult poll released Tuesday did not register any support for Swalwell's candidacy among those surveyed.