After 10 years in the U.S. House of Representatives, Congressman Mo Brooks has announced he wants a seat in the Senate.

Brooks, who represents Alabama’s 5th District, including Limestone County, made the announcement Monday in Huntsville during a campaign rally at an indoor gun range. Stephen Miller, who was President Donald Trump’s top immigration policy adviser, endorsed Brooks to replace Sen. Richard Shelby.

“I can tell you that nobody over the last four years has had President Trump’s back more than Mo Brooks,” Miller said. “… Your vote for Mo Brooks will allow him to carry on the ‘America First’ agenda.”

He called Brooks a “fearless warrior for Trump,” saying Monday night would be known as “the night we began to take back our country.”

“America’s status as the greatest nation in world history is at risk. And it’s at risk from those within our country,” Brooks told the crowd. Later, he said, “We are a beacon of freedom and liberty for the world, and we need to stay that way.”

Brooks, 66, came under fire earlier this year for similar comments made at a pro-Trump rally ahead of a deadly riot Jan. 6 at the U.S. Capitol. Two House Democrats proposed that Congress censure Brooks, arguing that his remarks incited the mob that attacked the Capitol.

However, Brooks has said his remarks were only intended as a pep talk for the next election and that critics have misrepresented them.

Shelby said earlier this year that he would not seek reelection in 2022. Prior to Brooks, the only announced candidate in the race was Lynda Blanchard, Trump’s former ambassador to Slovenia.

Brooks first entered the political realm as a member of the state House of Representatives in the 1980s. He then served in various roles at the local and state levels before being elected to the U.S. House of Representatives in 2010. Brooks attempted to run for U.S. Senate in 2017 but lost in the primary election.

Brooks has served five terms in the House, where the former prosecutor joined the conservative Freedom Caucus. He serves on the Armed Services Committee and Science, Space, and Technology, two important committees for his North Alabama district.

“America cannot afford senators who cower in their foxholes,” Brooks said. He added, “As President Trump can vouch, I don’t cut and run. I stand strong when the going gets tough.”

Republican hopefuls in a state where Trump won 62% of the vote are expected to try to convince primary voters they are the rightful banner carriers for the Trump agenda. But some observers worry the race could crown a far-right nominee to replace one of the Senate’s most senior leaders with a deep establishment ties.

Republican former Rep. Bradley Byrne of Alabama said the winner of the GOP primary will likely be whoever can convince voters they are the best heir to Trump and his “Make America Great Again” agenda.

 — The Associated Press contributed to this story.