Hagel assumes the Cabinet position from retiring Defense Secretary Leon E. Panetta, who watched the confirmation battle on C-SPAN from his home in California, a Pentagon spokesman said. The incoming Defense secretary now inherits a Pentagon in turmoil. The sequester is almost certain to take effect at the end of the day on Friday, Minority Whip John Cornyn, R-Texas, predicted Monday, although he said lawmakers have “sympathy to the arbitrary nature of across-the-board cuts” and allowing agencies to manage those reductions “seems to make a lot of sense.” The Defense Department will absorb half of the $85 billion in cuts for fiscal 2013 and half of the $1.2 trillion in cuts scheduled over the next decade.

Earlier in the day, senators voted 71-27 to invoke cloture on Hagel’s nomination, with 18 Republicans voting to limit debate. Republicans then agreed to yield back their 30 hours of post-cloture debate time to set up a final vote later in the day.

It was the second attempt at limiting debate on the nomination. The first time, on Feb. 14, senators rejected cloture 58-40. After Obama nominated Hagel for the Defense secretary position Jan. 7, the nominee faced vigorous resistance from some Senate Republicans over past comments he made and positions he took on Israel, Iran and nuclear weapons.

“He was one of only two that voted against sanctions for Iran, one of only four that voted against an effort to make the Iran Revolutionary Guard a terrorist group,” said James M. Inhofe of Oklahoma. The Armed Services ranking Republican said Hagel and Obama “wistfully” look for a world free of nuclear arms, whereas Inhofe himself looks “wistfully back at the days of the Cold War,” when there were two predictable superpowers.

The vote draws to a close a contentious chapter in which GOP senators bitterly went after Hagel. Freshman Ted Cruz, R-Texas, notably implied during the Senate Armed Services markup that Hagel may have received money from “radical or extreme groups” because the nominee had not disclosed his finances beyond what the committee required. Hagel’s testimony before the Armed Services panel was shaky, prompting John McCain, R-Ariz., to call Hagel “the least impressive witness” he has ever seen in his 26-year tenure in the Senate. But despite the lackluster performance and the GOP’s best efforts, the Armed Services panel reported the Hagel nomination in a 14-11 party-line vote Feb. 12.