Former Trump adviser Peter Navarro reports to prison after Supreme Court denies stay of sentence

Former Trump White House adviser Peter Navarro remained defiant as he reported to prison on Tuesday, one day after the Supreme Court denied a stay of his sentence.

He was convicted in September of two counts of contempt of Congress for refusing to provide testimony and documents to the House Select Committee that investigated the Jan. 6 attack on the U.S. Capitol.

Navarro spoke Tuesday morning in a strip mall in West Miami near the prison where he will serve four months.

"I will walk proudly in there to do my time," Navarro said. "I will gather strength from this: Donald John Trump is the nominee."

Navarro called the case an "unprecedented assault on the constitutional separation of powers."

Speaking for about 10 minutes, Navarro spoke about Biden, expressed his support for Trump and said that "all [he] has done is [his] duty to this country."

He went on to mention former White House chief strategist Steve Bannon's contempt of Congress case and how Bannon was allowed to remain free from prison while he appeals his case.

Chief Justice John Roberts, in a short opinion, wrote Monday that he saw "no reason to disagree" with lower courts, which also rejected Navarro's request.

Navarro's appeal on the merits remains pending, but he will have to begin serving his sentence in the meantime.

Navarro was ordered on March 11 to report to prison on Tuesday.

He filed an emergency appeal to the Supreme Court last week in an attempt to remain out of prison as he works to overturn his conviction.

In testimony during Navarro's trial, former Jan. 6 committee staff director David Buckley said the House panel had wanted to question Navarro about efforts to delay Congress' certification of the 2020 election, a plan Navarro dubbed the "Green Bay Sweep" in his book "In Trump Time."

Navarro unsuccessfully argued that former President Donald Trump had asserted executive privilege over his testimony and document production.

-ABC News' Devin Dwyer contributed to this report.