Hagel, a decorated Vietnam veteran and Nebraska Republican, needed only a simple majority of 51 votes but first had to clear a filibuster mounted by his former GOP colleagues. The key vote came Tuesday morning when the Senate voted 71 to 27 to end the debate.
The four Republican senators voting in favor were Thad Cochran of Mississippi, Mike Johanns of Nebraska, Richard Shelby of Alabama and Rand Paul of Kentucky. All 41 no votes came from Republicans.
Hagel was seen as a controversial choice by his fellow party members who delayed his full vote two weeks ago. It was charged that he was too soft on Iran and hostile to Israel, and some Republicans used the nomination to demand more answers from the Obama administration on the attack on a U.S. mission in Benghazi, Libya -- which Hagel had nothing to do with.
Hagel is also seen as more likely to support the rapid withdrawal of U.S. troops from Afghanistan – a position that’s in line with President Barack Obama's – and Republicans were uneasy with the former senator’s opposition to the 2007 surge in Iraq.
Hagel will succeed Defense Secretary Leon Panetta.