Former Trump adviser Peter Navarro is bound for prison, after the Supreme Court on Monday denied his effort to remain free while he appeals his conviction for defying the House committee investigating the insurrection at the U.S. Capitol.

Navarro was sentenced to four months in prison in January after he defied a subpoena from the House select committee investigating the origins of the Jan. 6, 2021, Capitol attack. The former aide was convicted of two counts of contempt of Congress in September following a short trial, after prosecutors argued Navarro had acted as if he were “above the law.”

Chief Justice John Roberts turned down Navarro’s bid to stay out of prison on appeal on Monday after he argued that former President Donald Trump told him to invoke executive privilege to avoid testimony. A judge initially rejected Navarro’s efforts to remain free on appeal, saying the court had found no evidence Trump had “ever invoked the privilege.”

A panel of the U.S. Court of Appeals agreed that Navarro must begin his sentence after he failed to show any compelling legal argument “likely to result in reversal, a new trial, a sentence that does not include a term of imprisonment, or a reduced sentence of imprisonment.”

“I see no basis to disagree,” Roberts wrote in his brief decision.

Navarro’s attorneys had argued to the Supreme Court that executive privilege, if invoked, should have extended to Trump’s aides, and that legal questions remained about how those protections should be considered. The Justice Department, however, issued its own arguments that executive privilege “belongs to the executive branch, not to an individual present or former employee.”

Navarro must report to federal prison in Miami on Tuesday. He will be the first senior Trump aide to serve a sentence over his role in challenging the 2020 election.

Former White House adviser Steve Bannon has also been convicted for contempt of Congress, but has remained free while he appeals that decision.