Democratic candidate Bob Kerrey is expected to announce a major endorsement in his battle to win a U.S. Senate seat in Nebraska, his campaign said. A Kerrey campaign official said an announcement would be made Thursday that former Sen. Chuck Hagel, a Republican, would be endorsing Kerrey\'s bid to win the seat being vacated by Sen. Ben Nelson, a Democrat, who is retiring, The Wall Street Journal reported. Kerrey, a former U.S. senator and governor, has been in a tough battle with Republican state Sen. Deb Fischer to succeed Nelson. Hagel was in the U.S. Senate from 1996 to 2008 and has a reputation for being an individualist and crossing political lines. Hagel and Kerrey served together in the Senate and both are Vietnam War veterans who developed a friendship, the Omaha World-Herald reported. Recent polls indicated the race, considered crucial if the Republicans are to take over the Senate, is tightening. A World-Herald poll this week indicated Kerrey trailed by 3 percentage points. Republicans downplayed the endorsement, saying Hagel hasn\'t lived in Nebraska since he left the Senate. \"They have long been friends. It\'s not a surprise,\" Nebraska Republican Party Chairman Mark Fahleson said. \"It\'s just another out-of-touch, longtime Washington insider endorsing another out-of-touch Washington insider. At the end of the day, Chuck Hagel has long lost touch with Nebraskans.\"