Republican opposition to the appointment Chuck Hagel as US secretary for defense appeared to be solidifying after a day of combative Senate hearings in which he was confronted repeatedly about his views on the war on Iraq, Israel and nuclear disarmament.

Hagel appeared at times to be poorly prepared for the gruelling eight hours of questioning and uncertain as he struggled to defend criticisms of the US military surge in Iraq and votes against sanctioning Iran, and backtracked on statements characterising Israel as caging Palestinians like animals.

Republican senators accused Hagel of holding "extreme views" and endangering US security. Some said that based on his testimony they would vote against his confirmation, including Marco Rubio, Republican of Florida.

"Obviously, statements he's made about Israel…I just don't believe I will be able to support his nomination especially after his testimony in the last hour here, he's really not said anything that addresses those concerns to my satisfaction," he told Fox News.

However, although some Democratic party senators also expressed concerns about Hagel's views, he is still expected to win sufficient support from the Senate armed services committee and then the full Senate to receive confirmation.

Some of the sharpest exchanges of the hearing was between Hagel and his old friend Senator John McCain who sought to pin the nominee down over whether he stood by his opposition to the 2007 American troop surge in Iraq which Hagel described as the most dangerous US blunder since Vietnam.

McCain told Hagel that he has "fundamental disagreements" with some of

the nominee's positions and that he questioned the "quality of your professional judgement". Several years ago, the two men fell out of the invasion of Iraq, which Hagel openly questioned.

McCain pressed Hagel to say whether he stood by his opposition to the surge of troop leves in Iraq. "Are you going to answer the question, Senator Hagel? The question is whether you were right or wrong," said McCain.

Hagel said he was not going to give a yes or no answer, but McCain came back at him. "I think history has already made a judgement about the surge sir, and you're on the wrong side of it," he said.

Returning to the subject later in the hearing, Hagel talked about his service in Vietnam in 1968, a year in which 16,000 US soldiers died.

He said that with that in mind he asked himself before each vote on the Iraq war whether it was worth sending so many soldiers to fight and "in many cases to their deaths".

"I always asked the question: Is it worth the sacrifice?" he said, noting that 1,200 Americans were killed in the surge. "Was it necessary? I'm not so sure," he said.

Hagel also noted that the attack on Iraq was at the expense of the war in Afghanistan, the source of the 9/11 attacks.

After the hearing, McCain told Politico he had not made up his mind

whether to vote in favour of Hagel.

"The fact that he wouldn't answer a straightforward question was disappointing," he said "We expect witnesses to answer the questions, and he refused to do so."

But it was Hagel's views on Israel that drew repeated and intense questioning from Senators from both parties. At times, the hearing appeared more like the confirmation of a secretary of state than the head of the department of defense as Hagel was asked whether a peace agreement between the Israelis and Palestinians should be based on 1967 borders.

The questioning was prompted in part by Hagel's long history of criticisms of Israel and its influence in Washington. Several senators picked up on Hagel's statement in an interview for a book that the "Jewish lobby" intimidates many members of Congress.

Hagel repeated an earlier apology for using Jewish lobby, saying he should have referred to "pro-Israel lobby". Senator Roger Wicker, Republican of Mississippi, pressed Hagel. "Do you stand by your statement they succeed in this town because of intimidation?" he said.

Hagel said he should have described it as influence not intimidation.

Senator Lindsey Graham, Republican of South Carolina, picked up on the issue when he demanded that Hagel name any senator who has been "intimidated by the Israeli lobby" and identify a "dumb thing" Congress has been pressured to do by groups supportive of the Jewish state. "I didn't have in mind a specific person," said Hagel, apparently choosing to sidestep further controversy instead of backing up a view widely shared by other critics of the pro-Israel lobby in Washington. "I can't give you an example."

Graham also attacked Hagel for his refusal as a senator several years ago to sign a letter in support of Israel. "The lack of signature by you sends chills up my spine," said Graham.

Senator Mike Lee, Republican of Utah, pressed Hagel on whether he was prepared to defend a statement in which he said that the Israelis "keep Palestinians caged up like animals". Hagel pulled back. "If I had an opportunity to edit that, like many things I've said, I would like to go back and change the words and the meaning," he said.

Senator Jim Inhofe, Republican of Oklahoma, said he would not vote to confirm the nominee as secretary for defense. "His record demonstrates what I view as a steadfast opposition to policies that diminish US power and influence throughout the world, as well as a recent trend of policy reversals that seem based on political expediency rather than on core beliefs," he said.

Inhofe, like other senators, zeroed in on Hagel's vote as a senator against labelling the Iranian Revolutionary Guard Corps a terrorist organisation and imposing sanctions against it.

Hagel said he was one of 22 senators who took the same position. He was against the move because the US has "never, ever designated a part of a legitimate government, a state" as a terrorist organisation.

He said the vote would have permitted the US to use force against Iran and America was already in two wars at the time. Hagel noted that John Kerry, the new secretary of state, Joe Biden, now the vice president, also voted against the measure in the Senate.

Hagel was pressed about his opposition to unilateral sanctions against Iran a decade ago, and said that was a different time. He said he regards Iran a state sponsor of terrorism. Inhofe asked Hagel: "Why do you think the Iranian foreign ministry so strongly supports your nomination for secretary of defense?"

Exasperated, Hagel responded that he had no idea. "I have a difficult time enough with American politics," he said.

Later in the hearing, Inhofe said it had been suggested to him that the question about Iran's view of Hagel was disrespectful and asked the nominee if he felt disrespected. Hagel said not, and that Inhofe was entitled to ask the question.

• This article was amended on 1 February 2013. Lindsey Graham is the senator for South Carolina, not North Carolina. This has been corrected.