* Confirmation likely, but hearing will be testy
* Israel, Iran, budget among top issues for senators
* Hagel has been on charm offensive amid tough lobbying
By Patricia Zengerle and Phil Stewart
WASHINGTON, Jan 31 (Reuters) - Chuck Hagel will face tough questions on Pentagon spending cuts and U.S. relations with Israel and Iran on Thursday as he faces a deeply skeptical Senate panel considering his nomination to be President Barack Obama's next secretary of defense.
Another member of Obama's second-term national security team, Senator John Kerry, sailed through his confirmation before being receiving the Senate's overwhelming support on Tuesday.
But Hagel, a former Republican senator and decorated Vietnam War veteran who broke with his party over the Iraq War, can expect a much more confrontational hearing when he is grilled on a range of issues by members of the Senate Armed Services Committee.
Although most observers expect Hagel will eventually be confirmed - barring unexpected fireworks at the hearing - Thursday's testimony will be contentious.
At least three Republican panel members, including James Inhofe, the party's leader on the committee, have said they did not support Hagel's nomination.
"We are simply too philosophically opposed on the issues for me to support his nomination," Inhofe said in a Jan. 15 statement. Such comments have angered Hagel supporters, who say two-term senator, who would be the first former enlisted soldier to lead the Pentagon, deserves at least a hearing.
Hagel's confirmation hearing is set for 9:30 a.m. EST (1430 GMT) on Thursday.
In the entire Senate, which would vote on Hagel if he is cleared by the committee, only one of the 45 Republicans - Mississippi's Thad Cochran - has come out in Hagel's favor.
He is expected to face tough questioning on Israel and Iran, his view of the Pentagon budget - Hagel is known as an advocate for tighter spending controls - and relations with China.
The Middle East, which has been the most intense focus of the anti-Hagel campaign, is likely to be the toughest issue.
"There's a lot of misleading information out there about the senator's views on Middle East policy. Senators are going to want to hear from Chuck Hagel directly on what his view is and what is the administration's view," said Mark Jacobson, a senior fellow at the German Marshall Fund and a former staffer on the Senate Armed Services Committee.
Hagel, backed by the White House and Pentagon, has been on a charm offensive to win over recalcitrant senators since Obama nominated him this month to replace outgoing Defense Secretary Leon Panetta.
Facing a public campaign against his appointment by critics seeking to portray him as soft on Iran, anti-Israel and uncommitted to equal rights for women and gays, Hagel has been pounding the halls of the Capitol to hold one-on-one meetings with 53 senators before his hearing.
Susan Collins of Maine, a moderate Republican, said on Tuesday she had spoken with Hagel for 90 minutes and been satisfied on several issues, but stopped short of endorsing him.
"We had a good discussion, but it's obvious that we have very different views on some fundamental issues," she said.
Hagel also detailed his views in 112 pages of written responses to wide-ranging questions submitted by lawmakers.
In them, he said that if confirmed as the next defense secretary, he would ensure that the military is prepared to strike Iran if necessary but stressed the need to be "cautious and certain" when contemplating the use of force.
Hagel also voiced support for a steady U.S. drawdown in Afghanistan, pledged to ensure equal treatment for women and homosexuals in the military and assured the committee that the United States would maintain an "unshakeable" commitment to Israel's security.
Most observers expect Hagel will be confirmed by the committee, even if he is approved only 14-12, along party lines.
"I do think he'll be voted out of committee tomorrow and then it will be interesting to se where things go on the Senate floor," said Maren Leed, a senior adviser at the Center for Strategic and International Studies.
In the face of intense lobbying by both Hagel supporters and opponents, many Republicans have said they will withhold judgment until after the hearing.
Democrats control 55 seats in the Senate and can approve Hagel with no Republican support, but they will need some backing from Hagel's party to overcome procedural hurdles that could stop the nomination.
One has already emerged. Senator Lindsey Graham, a committee member, has threatened to keep the nomination from going to the Senate floor if Panetta does not testify about a September attack on the U.S. diplomatic mission in Benghazi, Libya.
Democratic Senator Carl Levin, the committee's chairman, said Panetta is already due to testify, and that would take place before the full Senate voted on Hagel. (Editing by Doina Chiacu)