DANBURY, Conn. — Longtime Trump ally Steve Bannon was taken into custody Monday after surrendering at a federal prison to begin a four-month sentence on contempt charges for defying a subpoena in the congressional investigation into the U.S. Capitol attack.

Bannon arrived at the Federal Correctional Institution in Danbury around noon Eastern time and was formally taken into federal custody, the Bureau of Prisons said.

Speaking to reporters, Bannon called himself a “political prisoner,” said former President Donald Trump was “very supportive” of him and slammed Democrats, including Attorney General Merrick Garland.

“I am proud of going to prison,” Bannon said, adding that he was “standing up to the Garland corrupt DOJ.”

Shortly before he arrived to surrender, a small group of supporters gathered on the side of the road outside the prison. They cheered as Bannon and GOP Rep. Marjorie Taylor Greene of Georgia spoke during a news conference, holding up flags and signs supporting Bannon as a small group of protesters shouted “Lock him up!” and “Traitor!”

A judge had allowed Bannon to stay free for nearly two years while he appealed but ordered him to report to prison Monday after an appeals court panel upheld his contempt of Congress convictions. On Friday, the Supreme Court rejected his last- minute appeal to stave off his sentence.

A jury found Bannon guilty of two counts of contempt of Congress: one for refusing to sit for a deposition with the Jan. 6 House Committee and a second for refusing to provide documents related to his involvement in the Republican ex-president’s efforts to overturn his 2020 election loss to Biden.

Defense attorneys have argued that the case raises issues that should be examined by the Supreme Court, including Bannon’s previous lawyer’s belief that the subpoena was invalid because Trump had asserted executive privilege. Prosecutors, though, say Trump had never invoked executive privilege in front of the committee.