Chuck Hagel fielded heated questioning Thursday from Republicans regarding his record on Iran sanctions, Israel and nuclear weapons, but President Barack Obama’s pick to be the next Pentagon chief did not appear to suffer any fatal blows.

During his confirmation hearing before the Senate Armed Services Committee, Hagel was, as expected, forced to defend, amend, explain or retract statements he had previously made on a wide range of issues.

Hagel stumbled a few times, including accidentally saying he supported the president’s policy on containing Iran, an error he quickly corrected. But Democrats largely worked to help him hew closely to the Obama administration’s policy lines.

Addressing concerns that his positions have been too soft on Iran, Hagel acknowledged that he was “part of an effort” in 2008 to block Iran sanctions legislation from being debated on the Senate floor. But he also provided assurances that many lawmakers have been waiting to hear, including his support for a policy of prevention, rather than containment, on Iran and, if necessary, unilateral sanctions on Tehran.

“Unilateral sanctions, because we’ve already got strong international sanctions, should be considered,” Hagel said. “I think the president is right to consider those. I would support those.”

The nominee also sought to correct his remarks to an author who quoted him as saying, “the Jewish lobby intimidates” many lawmakers into making “dumb” decisions regarding Middle East policy. Hagel’s most outspoken opponents have branded him an anti-Semite for his reference to the “Jewish lobby.”

Hagel apologized, saying he should have referred to “the pro-Israel lobby.” He also said he regretted the use of the term “intimidate,” saying he should have used the word “influence.” And he pulled back on his “dumb” characterization, acknowledging that “there are different views on these things.”

The former Republican senator from Nebraska also stressed that a much-publicized nuclear disarmament report he co-wrote last year merely set an “illustrative” example of a reduction in the nuclear arsenal rather than a hard and fast set of recommendations — an argument that many Republicans did not buy.

Sen. Kelly Ayotte of New Hampshire called Hagel’s comments “troubling and inconsistent.” But his stated commitment Thursday to maintaining and modernizing the nuclear arsenal, and his opposition to unilateral reductions to the U.S. nuclear inventory, may be enough to sway some lawmakers who remain on the fence over his nomination.

Hagel, who joked that more attention has been paid to his words in the past eight weeks than he ever thought possible, made clear that no single vote, quote or statement defines him, his beliefs or his record.

“My overall worldview has never changed: that America has and must maintain the strongest military in the world; that we must lead the international community to confront threats and challenges together, and take advantage of opportunities together; and that we must use all our tools of American power to protect our citizens and our interests,” said Hagel, a Vietnam veteran. “I believe, and I always have believed, that America must engage in the world, not retreat from the world.”

In his opening statement, Hagel stood by his record during his two terms in the Senate, during which he cast more than 3,000 votes, as well as his work since leaving Capitol Hill. But he also conceded throughout the hearing that he has made mistakes along the way.

“Like each of you, I have a record. A record that I am proud of, not because of any accomplishments I may have achieved, or certainly because of an absence of mistakes, but rather because I’ve tried to build that record based on living my life and fulfilling my responsibilities as honestly as I knew how and with hard work,” he said.

One testy early exchange Thursday concerned one of those elements of Hagel’s record: his opposition to the Iraq war. Sen. John McCain of Arizona pressed Hagel on whether he now believes he was right to oppose the 2007 surge of troops in Iraq, a stance that put the former Nebraska senator at odds with McCain and other members of his own party.

McCain balked when Hagel refused to give him a simple answer.

“I think history has already made a judgment about the surge, sir, and you were on the wrong side of it,” McCain said. “Your refusal to answer whether you were right or wrong about it is going to have an impact on my judgment as to whether to vote for your confirmation or not.”

Later, Hagel pointed out that almost 1,200 members of the U.S. military were killed during the surge of forces in Iraq.

“Was it required? Was it necessary? Sen. McCain has his own opinion,” Hagel said. “I’m not sure. I’m not that certain it was required. It doesn’t mean I’m right. It doesn’t mean that I didn’t make wrong votes.”

Hagel, who acknowledged that he personally opposed Obama’s decision to surge troops into Afghanistan, said he now backs the White House’s plan in the country.

“There is little question, and I support completely, where the president wants to go in Afghanistan and his commitment to unwind that war,” he said.

Hagel’s work since leaving Congress has included the report he co-wrote last year with retired Gen. James E. Cartwright, the former vice chairman of the Joint Chiefs of Staff, that called for sharp reductions in the U.S. nuclear arsenal and, eventually, standing down the land leg of the nuclear triad of air, sea and land delivery platforms.

Cartwright and the other authors of the report have stressed that any reductions in the U.S. inventory must be done as part of bilateral negotiations with Russia, not unilaterally. In his opening statement, as well as in written responses to questions submitted in advance of Thursday’s hearing, Hagel stood by plans to modernize the country’s nuclear assets.

“I am committed to maintaining a modern, strong, safe, ready and effective nuclear arsenal,” he said. “America’s nuclear deterrent over the last 65 years has played a central role in ensuring global security and the avoidance of a World War III.”

During his questioning of Hagel, Sen. James M. Inhofe of Oklahoma, the top Republican on the Armed Services panel pressed the nominee about his involvement in the nuclear report, which was put out by the non-proliferation group Global Zero. Hagel stressed that he has always supported international disarmament talks — a position, he said, that dates back to President Ronald Reagan.

“We aren’t going to unilaterally disarm,” he responded.

Echoing the administration’s own talking points, Hagel assured the panel that his policy on Iran would be one of prevention, not containment. He also said he would ensure that Israel maintains its “qualitative military edge” in the region and pledged to support efforts like the Iron Dome missile defense system.

In a move to dispel any doubts about his support for Israel, he strongly reaffirmed the U.S. relationship with the Jewish state.

“I absolutely support the continuation and strengthening of our relationship with Israel,” he declared, adding that he would “maintain and enhance” the U.S. commitment to Israel’s qualitative military edge over its Arab adversaries.

Several GOP senators, including Inhofe, have already vowed to vote against Hagel’s nomination, pointing to concerns that he is too soft on Iran and not committed to modernizing the military’s nuclear arsenal. On Thursday, Sen. Marco Rubio, R-Fla., announced that he plans to vote against Hagel.

In his opening remarks Thursday, Inhofe called Hagel’s record “deeply troubling and out of the mainstream” and said he has too often been willing to subscribe to a worldview of “appeasing our adversaries while shunning our friends.”

Many other Republicans, including moderates such as Susan Collins of Maine, have said their vote on Hagel’s nomination hinges on how he fields questions at the confirmation hearing.

The Democratic chairman of the Senate Armed Services Committee, Carl Levin of Michigan, addressed Hagel’s previous statements on Iran, particularly his comments that unilateral sanctions are ineffective at isolating Iran.

“While effective multilateral sanctions are preferable, unilateral sanctions are an important part of the approach that the Obama administration has followed and Congress has supported, and it appears that sanctions are producing tremendous pressure on Iran,” Levin said.

In response to questions from Levin, Hagel explained his earlier opposition to unilateral sanctions, saying that it was a “different time.”

“We were in a different place with Iran during that time,” Hagel said. “It was never a question of did I disagree with the objective,” he added.

Many Democrats have been noncommittal about Hagel as well, but most are expected to endorse his nomination.

Addressing some concerns from the left, Hagel said he is committed to continuing the implementation of the repeal of the 1993 “don’t ask, don’t tell” law. He also said he would do “everything possible under current law to provide equal benefits to the families of all our servicemembers,” a nod to gay rights advocates who have pushed to extend benefits to the families of gay members of the military.

In addition, Hagel said he supported the Pentagon’s decision last week to open ground combat positions to women and would work with the Joint Chiefs of Staff to implement the historic change in policy.

Jonathan Broder contributed to this report.