Former U.S. senator Chuck Hagel testifies on Jan. 31, 2013 during a Senate Armed Services Committee hearing on his nomination to be defence secretary. (REUTERS)

WASHINGTON - The Senate voted to confirm Chuck Hagel on Tuesday as President Barack Obama's new secretary of defence.

Senators backed the nomination by a 57-41 vote, as voting continued, with only about four Republicans joining Democrats in support of Hagel, a Republican former U.S. senator from Nebraska.

Hagel needed only 51 votes to be confirmed as the new civilian leader at the Pentagon.