Republican Secretary of State Wayne Williams on Wednesday referred a member of Colorado’s Electoral College delegation to the attorney general’s office for criminal investigation after the elector defected in Monday’s presidential vote.

Elector Micheal Baca of Denver, a Bernie Sanders supporter, became one of a handful of so-called “Hamilton Electors” in protesting the election of Republican Donald Trump.

Baca on Monday declined to back Democrat Hillary Clinton, who won the popular vote in Colorado, in an effort to block Trump and elect a compromise candidate. In doing so, Baca may have violated state law, which required him to back the candidate who won the popular vote in Colorado.

The plan was to convince fellow electors to vote for someone other than Clinton or Trump, thereby handing the election to a compromise candidate. The true target was other states where Trump won. The goal was to convince at least 37 Republican electors to vote for someone other than Trump, which would have sent the responsibility of electing the president to Congress.

The effort failed on Monday, as Trump secured the Electoral College votes necessary to become the nation’s 45th president.

Two Colorado electors-Polly Baca of Denver, no relation to Michael Baca, and Bob Nemanich of Colorado Springs-filed lawsuits in an effort to free electors from having to vote for the candidate who won the popular vote. But federal and state courts, including the 10th Circuit Court of Appeals in Colorado, ruled against the electors, declining to grant them immunity from state law.

Despite taking an oath on Monday swearing to vote for the candidate who won the popular vote, Baca still defected, which could leave him open to felony perjury charges.

Attorneys for Baca and other electors attempted to challenge the oath administered by Williams, but a Denver judge ruled that since the secretary of state’s office had administered the oath through rule-making, the electors had to take it in order to vote.

Despite the guidance from the judge, Baca wrote in Ohio Gov. John Kasich’s name, who he had hoped would become the compromise Republican candidate, despite Baca’s allegiance to Sanders. The idea was that Kasich would be better than Trump, albeit not the candidate Baca had hoped for in Sanders.

Baca could more likely face a misdemeanor charge for having failed to vote for Clinton.

“This was a violation of (state law) which requires: ‘Each presidential elector shall vote for the presidential candidate and, by separate ballot, vice presidential candidate, who received the highest number of votes at the preceding general election in this state,'” Deputy Secretary of State Suzanne Staiert wrote in a letter to the Colorado Attorney General’s office, citing the state statute.

Baca declined to offer any public statements following the vote on Monday, which took place inside the Colorado Capitol, as hundreds of anti-Trump protesters encouraged Baca to defect.

Baca was quickly relieved of his duties as an elector after he defected, and he was replaced with an elector who agreed to vote in accordance with the law.

The other eight Colorado electors backed Clinton.

A spokeswoman for the attorney general’s office said once the office receives the referral, which happened around noon on Wednesday, that it would review it “just as we do in all situations, and make an appropriate determination at that time.”