Sen. Chuck Hagel (R-Neb.) officially announced Monday that he will not run for a third term and does not plan to run for president in 2008, setting in motion a battle for his Senate seat and leaving anti-war Republicans and independents without one of their candidates of choice in the presidential contest.

Speaking at the Omaha Press Club about six months after balking at a decision on his political future, Hagel was definitive about his Senate plans and all but closed the book on a presidential bid.

“I will not seek a third term in the United States Senate, nor do I intend to be a candidate for any office in 2008,” Hagel said. “It has been my greatest honor and privilege to serve my country and represent my fellow Nebraskans in the U.S. Senate. My family and I will be forever grateful for this opportunity and the trust placed in me by the people of Nebraska. It has enriched all of us.”

Hagel, a conservative Vietnam Veteran who recently became a leading Republican voice against the Iraq War, earlier this year had toyed with the idea of a presidential bid and was noncommittal about staying in the Senate.

Some had speculated that he might spurn the GOP and join an independent presidential ticket, possibly with New York Mayor Michael Bloomberg, who recently switched from Republican to independent.

Hagel called a widely attended press conference in March, only to say he would continue to delay a decision on his future. The move earned him a degree of ridicule. He defended it by saying he had promised his constituents that he would address his future at that point.

At the time, Hagel suggested that he wanted to run for president but was concerned about its impact on his family. He said the decision was easy from a political standpoint.

His departure opens up the Nebraska Senate race to two leading contenders -- former Sen. Bob Kerrey (D-Neb.) and Agriculture Secretary Mike Johanns (R) -- who were unlikely to run if Hagel opted for reelection.

Hagel also faced a primary challenge from two GOPers, state Attorney General Jon Bruning and former Rep. Hal Daub (Neb.). Businessman Tony Raimondo and financial adviser Pat Flynn have also entered the Republican primary field.