Defense secretary nominee Chuck Hagel endured a barrage of criticism Thursday during his all-day confirmation hearing on Capitol Hill, challenged repeatedly by Republican lawmakers about his past positions on Israel, Iran, Iraq and other issues he'd be sure to confront at the helm of the Pentagon.

The former Nebraska Republican senator was compelled under questioning to walk back a series of past statements, including one in which he complained about the "Jewish lobby." He had several sparring partners throughout the day, but was questioned perhaps most aggressively by fellow Vietnam War veteran Sen. John McCain and freshman Texas Sen. Ted Cruz, both Republicans.

Hagel was caught by surprise when Cruz played two tapes from appearances on Al Jazeera -- one of which showed him not challenging a caller who accused Israel of war crimes, another in which he appeared to agree with the assertion that America is "the world's bully."

Of the Israel interview, Cruz said: "The caller suggests that the nation of Israel has committed war crimes, and your response to that was not to dispute that characterization." He then asked Hagel directly whether he thinks Israel has committed war crimes.

"No, I do not," Hagel said, while saying he wanted to see the "full context" of the interview.

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Cruz called the war-crimes suggestion "particularly offensive given that the Jewish people suffered under the most horrific war crimes in the Holocaust."

"I would also suggest," he continued, "that for ... a prospective secretary of Defense not to take issue with that claim is highly troubling."

Cruz then played the tape of Hagel being asked about the perception and "reality" that America is the world's bully. Hagel could be heard calling the point a "good one."

Cruz said the answer is "not the conduct one would expect of a secretary of Defense."

Hagel disagreed with Cruz' characterization of his answers. Further, Senate Armed Services Committee Chairman Carl Levin said he had told Cruz he would have preferred he use a transcript and not air that interview. Levin, a Democrat, later said he thought Hagel "really advanced his own cause" at the hearing.

The incident, though, was one of several confrontations Thursday as the committee considered Hagel's nomination to succeed Leon Panetta at the Pentagon. Hagel is among the most controversial of President Obama's second-term Cabinet nominees. The committee adjourned late Thursday afternoon without voting on the nomination.

Just days earlier, Sen. John Kerry easily won confirmation to be secretary of State.

Hagel, though, did not enjoy such a warm reception.

It was the troop surge in Iraq that became a flashpoint between McCain and Hagel during Thursday's hearing. McCain repeatedly tried to get Hagel to answer whether he was "right or wrong" when he once called the troop surge a "dangerous foreign policy blunder."

"I'm not going to give you a yes or no -- I think it's far more complicated than that. ... I'll defer that judgment to history," Hagel said, adding that he was referring to both the overall Iraq war, as well as the surge, in that comment

McCain fired back: "I think history has already made a judgment about the surge, sir, and you're on the wrong side of it."

The senator added that Hagel's "refusal" to answer the question "will have an impact" on whether he votes for his nomination.

McCain's position on Hagel could be a significant bellwether for his nomination. The two veterans once had a close relationship during their years in the Senate, but politics and Hagel's opposition to increased troop numbers in Iraq divided the two men.

In order to have a lock on the nomination, Hagel would need the support of all Senate Democrats and at least five Republicans -- just in case Republicans call for a 60-vote threshold to proceed to the confirmation vote. It's possible Hagel would not need that many, though.

Hagel, during the hearing, urged lawmakers not to write him off based on a string of controversial votes and quotes from his career in the Senate.

"Like each of you, I have a record," Hagel said Thursday. "A record that I'm proud of. I'm proud of my record 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 continued: "But no one individual vote, no one individual quote, no one individual statement defines me, my beliefs, or my record. My overall worldview has never changed: that America has and must maintain the strongest military in the world; that we must lead in the international community to confront threats and challenges together ... that we must use all our tools of American power to protect our citizens and our interests."

He noted he's cast "over 3,000 votes" during his time in the Senate and given "hundreds of interviews and speeches."

But the top Republican on the Armed Services Committee, Sen. Jim Inhofe of Oklahoma, announced at the start of the hearing that he would be opposing Hagel.

"On many of the security challenges facing U.S. interests around the world, Senator Hagel's record is deeply troubling, and out of the mainstream. Too often it seems he's willing to subscribe to a worldwide view that is predicated on appeasing our adversaries while shunning our friends," he said. Further, he accused Hagel of recent "reversals" in his opinions "that seem based on political expediency rather than on core beliefs."

Levin, D-Mich., also said Hagel's positions -- including opposition to unilateral sanctions on Iran and criticism of efforts to isolate both Syria and Hamas -- must be "explored at this hearing."

Still, he said Hagel -- as a veteran -- has "critically important qualifications" of understanding the consequences of using military force.

Hagel later defended his opposition to unilateral sanctions on Iran, saying he took that position a decade ago, which he described as a "different time." He did at one point describe the Iran government as "legitimate."

As for claims that he's got a shaky position toward Israel, he said "I've never voted against Israel ever in the 12 years I was in the Senate."

Two former committee chairmen -- Democrat Sam Nunn and Republican John Warner -- introduced and endorsed the nominee at the top of the hearing.

If confirmed, Hagel, a decorated Vietnam combat veteran, would be the first enlisted man and first Vietnam veteran to serve as defense secretary.

Hagel has the announced backing of about a dozen Democrats and the tacit support of dozens more who are unlikely to embarrass the president by defeating his Cabinet pick. One Republican -- Sen. Thad Cochran of Mississippi -- has said he will vote for his former colleague.

Six Republicans, including four members of the Armed Services panel, have said they will oppose Hagel's nomination.

A recent Fox News poll showed 34 percent of voters saying they would vote to confirm Hagel, while 25 percent would not. The rest had not heard of him.

Sen. Lindsey Graham, R-S.C., earlier this month described Obama's selection as an "in-your-face" pick but was a bit less critical this week.

Hagel testified Thursday that he is committed to Obama's national security agenda. Addressing concerns about his stance on Iran, he said "all options must be on the table" to prevent Iran from obtaining a nuclear weapon.

He also said it's important that the county "not hesitate to use the full force" of the military in defense of security, "but we must also be smart, and more importantly wise," in how that power is employed.

The hearing was the first time Hagel publicly addressed the barrage of criticism that he is not sufficiently pro-Israel or tough enough on Iran. Hagel has also been criticized for his comments about the influence of a "Jewish lobby" and his view of gay rights. Hagel apologized for the "Jewish lobby" comment Thursday.

He addressed several of the issues in a 112-page questionnaire to the committee in which he said his wartime experience would shape his decisions about using military force.

In his responses, Hagel adopted a hard line on Iran and its possible pursuit of a nuclear weapon. He echoed Obama's view that all options are feasible to stop Tehran, praised the rounds of penalties and warned of "severe and growing consequences" if Iran balks at international demands.

The Associated Press contributed to this report.