WASHINGTON (CNN) -- Former Nebraska Senator Chuck Hagel's rocky and inauspicious path to leadership of the Pentagon could haunt him if he doesn't watch his step.
"If people feel Hagel makes a mistake in the future, they will come after him even harder than if this ugly process of recent weeks hadn't happened," said Michael O'Hanlon, a senior fellow at the Brookings Institution and a co-author of "Bending History: Barack Obama's Foreign Policy."
Hagel's nomination as defense secretary was subject to harsh criticism from some Republicans over past statements on sensitive political and national security matters.
His shaky performance at his confirmation hearing and subsequent political wrangling over his selection and on unrelated matters did not help his case.
But efforts to further delay his nomination were swept away on Tuesday as the Senate confirmed him, 58-41.
The task for Hagel going forward is to swiftly move past the protracted nomination battle, prove himself a strong and capable Pentagon chief, and repair relationships on Capitol Hill, said Fran Townsend, a former homeland security adviser to President George W. Bush.
"Of course, when he walks through the door he is bruised and battered. But I think we shouldn't overestimate the impact of that," Townsend said. "Frankly, once he is confirmed as secretary of defense and once he sits in the seat and takes on the mantle of responsibility, everyone in the Pentagon is going to stand up and salute smartly, as well they should."
O'Hanlon said Hagel would not "be damaged goods" and the political outcry over his nomination would quickly be overshadowed by the latest budget drama engulfing Washington over spending cuts.
Those bad feelings about Hagel stem, in part, from his 2007 comments that the "Jewish lobby intimidated lawmakers." Republicans who are already uncomfortable with President Barack Obama's policies toward Israel are uneasy about a defense secretary holding such views.
The decorated Vietnam veteran's criticism of the Iraq War, the Patriot Act, and his past positions on Iran and on U.S. military intervention also raised red flags with his opponents.
In 1998, he spoke about an ambassadorial nominee as being "openly, aggressively gay," remarks for which he has since apologized.
And Hagel hasn't been sparing in his criticism of conservative and GOP figures, saying radio show hosts like Rush Limbaugh "try to rip everybody down" but "don't have any answers," and labeling George W. Bush as callous on Iraq when he was president.
Last week, 15 GOP senators sent a letter to Obama calling on him to withdraw Hagel's nomination.
Arizona Sen. John McCain, the ranking Republican on the Senate Armed Services Committee and a fierce Hagel critic, did not sign the letter. But he led the charge against him in the Senate, stalling the nomination at one point in exchange for more information from the White House on the deadly September terror attack on the U.S. diplomatic mission in Benghazi, Libya. That sentiment gained traction in conservative circles.
"There is simply no way to sugar coat it. Senator Hagel's performance before the Senate Armed Services Committee was remarkably inept and we should not be installing a defense secretary who is obviously not qualified for the job and who holds dangerously misguided views on some of the most important issues facing national security policy for our country," said Republican Sen. John Cornyn of Texas.
There was a healthy serving of politics behind the Hagel pushback, some experts say. He isn't the only potential member of the Obama Cabinet to be grilled during the nomination process.
"There is an element of strategic calculation going on here," Alan Abramowitz, a political science professor at Emory University, said recently.
Some Republicans also believed that Hagel, like Susan Rice, was vulnerable, according to political experts.
Rice, the U.S. ambassador to the United Nations, withdrew her name from consideration for secretary of state after drawing heavy criticism from McCain and other Republicans over her public statements about the Benghazi attack.
Moreover, at the start of his first term, Obama's pick to lead the Treasury Department, Timothy Geithner, emerged from a tough confirmation fight in the wake of recession to help push through Wall Street reform as well as the banking and auto industry rescues. His successor, Jack Lew, is expected to be confirmed.
A Democratic proponent of Hagel's, Sen. Claire McCaskill of Missouri, said Sunday the president's choice to head the Pentagon was receiving undue criticism from Republicans.
"The president wants him in the room as he's making important decisions. There's no question about his integrity of character. I think the president deserves to have the Cabinet he wants as long as the person is qualified," she said on "Fox News Sunday."
"He's qualified, and I think it's despicable how his character has been impugned by some people through innuendo and inference," McCaskill added.
The consternation over Hagel's confirmation has been "kabuki theater," said David Rothkopf, editor of Foreign Policy magazine.
"The political divisions that dictated the pace and twists of his confirmation process pre-date him and will post-date his confirmation," Rothkopf said. "The reality is that Hagel won't drive (defense) policy, the president and Hill politics will."
And time will heal even these political wounds, Rothkopf said.
"The margin of his confirmation victory won't impact this in any way except perhaps in terms of rhetoric," he said.
Hagel will face tough challenges in succeeding Leon Panetta at the Defense Department. The agency faces massive budget cuts through previous planning and through the pending congressional sequester, which takes effect on Friday absent congressional action to head it off.
He is also in charge of winding down U.S. combat operations in Afghanistan and, as a senior member of Obama's national security team, address threats to U.S. interests from global terrorists. The administration is also dealing with Iran's nuclear ambitions and the civil war in Syria, where stockpiled chemical weapons are a chief concern.
"He has got to make sure that his next appearance, his next testimonial appearance before Congress is, to use a too often used phrase, a slam dunk. That is he has got to go in there over prepared, very aggressive and willing to take on the hard questions in a way he seemed reluctant to do in his confirmation process," Townsend said.
CNN's Kevin Liptak and Barbara Starr contributed to this report.