WASHINGTON – Senate Republicans on Thursday blocked the nomination of former GOP senator Chuck Hagel as the nation's next defense secretary over unrelated questions about President Barack Obama's actions in the aftermath of the deadly raid on the U.S. diplomatic mission in Libya. Obama accused Republicans of playing politics with national security during wartime, and Democrats vowed to revive the nomination after Congress' weeklong break.

By 58-40, with one abstention, the Senate fell short of the 60-vote threshold required to advance Hagel's nomination to a final, up-or-down vote on his confirmation. Four Republicans voted with Democrats to end the debate and proceed to a final vote: Sens. Thad Cochran of Mississippi, Lisa Murkowski of Alaska, Susan Collins of Maine and Mike Johanns of Nebraska.

Obama reacted immediately, hammering Republicans for an unprecedented filibuster of a nominee for defense secretary and insisting that Hagel — a former two-term Republican senator from Nebraska and twice-wounded Vietnam combat veteran — will eventually win confirmation. He would succeed Defense Secretary Leon Panetta, who is stepping down after four years as CIA director and Pentagon chief.