But Sen. Claire McCaskill, D-Mo., suggested that the opposition to Hagel “wasn’t about resume, it was about ideology,” and she worried about the fallout.

“This is a scary time in the world, and their actions have diminished his effectiveness,” she said.

Opponents chastised Hagel for what they claimed were his views on Israel, while supporters said they took his statements out of context. They also complained about his views on terrorism, suggesting – even as they acknowledged that they had no evidence – that he had taken money from anti-U.S. governments. Critics also alleged he was affiliated with a group called "Friends of Hamas,” which turned out to be fictional.

Democrats said the attacks echoed the political witch hunts of the McCarthy era.

But Hagel’s performance before the Senate Armed Services Committee during his hearing did not win stellar reviews. He was halting and sounded uncertain at times during the questioning. But he was also often a loner amid the Republican Senate caucus when he served. Republicans have also never forgotten that he opposed the troop surge during the Iraq war.

A former infantry sergeant who was wounded twice in Vietnam, Hagel will become the first enlisted man to earn the top job at the Pentagon. During his confirmation hearing, he was described as a soldier willing to put himself in harm’s way.

“He feels a deep commitment to our men and women in uniform, and as the head of the Pentagon I know their interests will always be close to his heart,” Vice President Joe Biden, who served alongside Hagel in the Senate, said in a statement.