Former Republican Sen. Chuck Hagel will endorse Democratic Senate nominee Bob Kerrey at news conferences in Omaha and Lincoln on Thursday.
Hagel, a fellow Vietnam War veteran, served in the Senate with Kerrey for four years. Both were wounded in combat in Vietnam.
During their service together as Nebraska's two senators, the pair enjoyed an amiable and cooperative working relationship despite party differences.
Hagel left the Senate in 2009 after two terms, choosing not to seek re-election.
A fiscally conservative Republican who embraced the internationalist tradition of his party, Hagel drew sharp criticism from some Republicans for his outspoken and independent opposition to former President George W. Bush's Iraq war policies.
Hagel's endorsement is likely to anger conservative and loyalist Nebraska Republicans who are strong supporters of GOP nominee Deb Fischer, but it could appeal to moderate Republicans who embrace Hagel's views, as well as registered independents and undecided voters.
Hagel is a professor at Georgetown University in Washington and co-chairman of President Barack Obama's intelligence advisory board.
His endorsement follows on the heels of Wednesday's announcement that 2008 Republican presidential nominee, Ariz. Sen. John McCain, will come to Omaha on Friday to campaign with Fischer.
McCain also was wounded in the war and held captive in Vietnam. He served in the Senate with Kerrey and Hagel.
The Hagel support comes at a time when Kerrey appears to be closing in on Fischer in a number of Senate polls. Among them was one published in the Omaha World-Herald on Sunday that showed Kerrey moving within 3 points of Fischer.