Less than three weeks after Colorado State Sen. Owen Hill refused to give up his bid for a U.S. Senate seat, Hill is leaving the race and will give his support to the U.S. Rep. Cory Gardner.

Hill, of Colorado Springs, said in late February that Gardner used "corruption and backroom deals" to pressure him out of the running. On Monday, though, Hill said that "unity within the Republican Party" will be needed to gain back control of the Senate.

"With all the support Cory has, we need a united front," Hill said. "He has the ability to leverage a national network to beat Mark Udall."

Udall, a Democrat, is seeking re-election in this year's midterm vote. He was elected to the U.S. Senate in 2008 after serving five terms in the House of Representatives.

No incumbent U.S. Senator from Colorado has been beaten since 1978, when Republican Bill Armstrong beat Democrat Floyd Haskell.

Hill joins state Rep. Amy Stephens and Weld County District Attorney Ken Buck as main players who might have challenged Gardner in June's Republican primary but have opted out to clear a path for their would-be opponent.

Gardner announced his candidacy March 1, noting that now is the time to "stand up to those leading our country in the wrong direction."

Gardner has said his top campaign concern is Udall's support for the Affordable Care Act.

Hill said Monday that a Republican-dominated Senate would help counteract actions by President Barack Obama and the rest of the executive branch, which he said caters to "insiders and those with access" and ignores the desires of the American people.

"If we don't take the Senate back, I think my kids will be worse off for it," Hill said. "Government governs best when it governs closest to the people."

Hill's exit leaves Mark Aspiri, a businessman from Glenwood Springs, Floyd Trujillo and Sen. Randy Baumgardner of Cowdrey as the Republicans left to challenge Gardner.

Gardner could not be reached Monday for comment.