Former Massachusetts Gov. William Weld William (Bill) WeldRalph Gants, chief justice of Massachusetts supreme court, dies at 65 The Hill's Campaign Report: Biden visits Kenosha | Trump's double-voting suggestion draws fire | Facebook clamps down on election ads Biden picks up endorsements from nearly 100 Republicans MORE (R), who is running for the GOP presidential nomination, on Wednesday compared President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE to former President Nixon after Trump declared executive privilege over special counsel Robert Mueller Robert (Bob) MuellerCNN's Toobin warns McCabe is in 'perilous condition' with emboldened Trump CNN anchor rips Trump over Stone while evoking Clinton-Lynch tarmac meeting The Hill's 12:30 Report: New Hampshire fallout MORE's full report.

“Donald Trump seems determined to model his response to the Mueller investigation on Richard Nixon’s response to Watergate,” Weld said in a statement.

ADVERTISEMENT

“Like Nixon, he is inappropriately using executive privilege to try and prevent Congress from seeing evidence of his criminal conduct. The courts rejected that during Watergate, and they will reject it again here,” he added.

Weld, who announced last month that he would mount a primary challenge to Trump, also said in his statement that the Republican Party "deserves better."

“The Republican Party deserves better than a candidate who makes a mockery of our long-standing support for the rule of law,” he said. “And the American people deserve better than a President who uses the power of his office to protect himself, rather than advance our national interests.”

Trump on Wednesday invoked executive privilege as the House Judiciary Committee prepared to vote to hold Attorney General William Barr Bill BarrHarris faces pivotal moment with Supreme Court battle Hillicon Valley: DOJ proposes tech liability shield reform to Congress | Treasury sanctions individuals, groups tied to Russian malign influence activities | House Republican introduces bill to set standards for self-driving cars McCarthy threatens motion to oust Pelosi if she moves forward with impeachment MORE in contempt of Congress after Barr did not turn over an unredacted version of the Mueller report and its underlying materials despite a committee subpoena.

White House press secretary Sarah Huckabee Sarah Elizabeth SandersSarah Sanders on Trump's reported war dead criticism: 'Those comments didn't happen' Sarah Sanders memoir reportedly says Trump joked she should hook up with Kim Jong Un McEnany stamps her brand on White House press operation MORE Sanders defended the president's action, saying in a statement that Trump "has no other option than to make a protective assertion of executive privilege.”

Weld has been a frequent critic of Trump, saying that his behavior as outlined in the redacted Mueller report amounts to "criminal conduct and impeachable conduct" in an MSNBC interview. He clarified in the interview that he was not calling for Trump's impeachment.