WASHINGTON — Even before President Obama declared this month that “I have Israel’s back” in its escalating confrontation with Iran, pro-Israel figures like the evangelical Christian leader Gary L. Bauer and the conservative commentator William Kristol were pushing for more.

In a slickly produced, 30-minute video, the group that the two men lead, the Emergency Committee for Israel, mocked Mr. Obama’s “unshakable commitment to Israel’s security” and attacked his record on Iran as weak. “I’ll be brutally honest: I don’t trust the president on Israel,” Mr. Bauer, who unsuccessfully sought the Republican presidential nomination in 2000, said in an interview. “I think his record on Israel is abysmal.”

With Israeli leaders warning of an existential threat from Iran and openly discussing the possibility of attacking its nuclear facilities, pro-Israel groups on all sides have mobilized to make their views known to the Obama administration and to Congress. But it is the most hawkish voices, like the Emergency Committee’s, that have dominated the debate, and, in the view of some critics, pushed the United States closer to taking military action against Iran and another war in the Middle East.

“It’s not about Israel,” said Representative Eric Cantor, Republican of Virginia, the House majority leader and a key Congressional ally of Prime Minister Benjamin Netanyahu of Israel.

“It’s about the U.S.,” Mr. Cantor said in an interview. “It’s about our interests in the region. There have been a lot of conflicting messages coming out of the White House.”

Among those advocating a more aggressive approach toward Iran are prominent Republicans in Congress, like Mr. Cantor and Senator John McCain of Arizona; the party’s presidential candidates; groups like the Emergency Committee and the American Israel Public Affairs Committee, or Aipac; the so-called “neocons” from the George W. Bush administration who were strong proponents of the war in Iraq; pro-Israel evangelical Christians like Mr. Bauer, who is also active in the group Christians United for Israel; and many Democrats.

Urging diplomacy are liberal groups like J Street, which is helped by $500,000 a year in contributions from the liberal philanthropist George Soros, and Tikkun, a Jewish journal that has begun running newspaper advertisements here and abroad that urge, “NO War on Iran and NO First Strike!” Tikkun, based in Berkeley, Calif., is hoping to link its antiwar message with the Occupy protests.

“A lot of people talk about the ‘Israel lobby’ as if it’s a monolithic thing,” said Dylan Williams, head of government affairs for J Street. “It’s a myth. There is a deep division between those who support military action at this point and those who support diplomacy.”

Clear fissures have developed among pro-Israel groups — not only between hawks and doves over whether to use military force against Iran, but among hard-liners themselves over just how aggressively to confront it.

Sheldon Adelson, a billionaire casino owner who is a staunch supporter of Israel, was once a major donor to Aipac. But because of Aipac’s support for American aid to the Palestinian Authority, he has broken from the group. This year, Mr. Adelson has given at least $10 million, along with his wife, to support Newt Gingrich’s presidential campaign.

Like Mitt Romney and Rick Santorum, Mr. Gingrich has pushed for stronger support of Israel and attacked Mr. Obama’s policies on the Iranian issue as weak. He also described the Palestinians as an “invented people.”

The disagreements over what to do about Iran reflect the divisions among Jews themselves. In a survey of American Jews last September by the American Jewish Committee, an advocacy group, 56 percent of those polled said they would support American military action against Iran if diplomacy and sanctions failed, while 38 percent opposed it. Support was down slightly from a year earlier.

Rabbi Michael Lerner, a leader of Tikkun and an affiliated antiwar coalition of religious groups, said backers of diplomacy want to slow what they have seen as a “drumbeat to war” in recent weeks. Rabbi Lerner and other opponents of military action say the debate over Iran echoes the political climate in 2002 before the United States-led invasion in Iraq.

Representative Keith Ellison, a Minnesota Democrat who opposes military action against Iran, said, “The rhetoric is overblown.”

Those advocating military intervention “whip up fear and whip up doomsday scenarios,” Mr. Ellison said in an interview. “It has an effect. If nothing else, they’re making Obama talk about military options with regard to Iran.”

But Mr. Ellison is in the minority on Capitol Hill, where the debate over Israel and Iran was largely settled long ago.

Even in the oft-divided Senate, a measure last fall to impose tough economic sanctions on Iran passed 100-0 despite White House concerns. Beyond antiwar activists like Mr. Ellison and the recently defeated Representative Dennis J. Kucinich, an Ohio Democrat, or neo-isolationists like Representative Ron Paul of Texas, the Republican presidential candidate, there is almost no constituency in either party for anything other than tougher sanctions against Iran and clear expressions of solidarity with Israel.

In the standoff with Iran, it is the hawkish groups supporting military action that wield more money, political clout and high-profile names than do the advocates of a diplomatic solution.

In all, pro-Israel political action committees and donors affiliated with them have given more than $47 million directly to federal candidates since 2000, according to data from the Center for Responsive Politics, a nonpartisan research group. They rank among the top contributors to a number of prominent Democrats and Republicans, and pro-Israel groups have hosted many lawmakers on expense-paid trips to Israel. When Aipac featured Mr. Obama and Mr. Netanyahu at its conference this month, more than half the members of Congress attended.

Richard N. Perle, an influential neoconservative voice who served as a senior Defense official in the Bush administration, said he saw a growing “sense of urgency” among Republicans over the need to consider all options — including military intervention — to stop Iran from developing a nuclear bomb that could be used against Israel. The “noisy public debate” has now made military operations more politically viable for Mr. Obama, he said in an interview.

The president himself has warned against “loose talk of war” in the public debate over Iranian policy, even as he has left open the possibility of military action. At the Aipac conference, Mr. Obama reassured Israeli officials and supporters that he had “Israel’s back.” He referred explicitly to military action as an option for dealing with Iran and rejected a policy of containment. The harder line that Mr. Obama articulated also happens to be good domestic politics, according to experts. The president’s statements, they said, calmed the jitters of some Jewish voters about his support for Israel and defused the effort of Republican presidential candidates to use Iran as a wedge issue against him.

Steve Rabinowitz, who served in the Clinton administration and now advises Jewish groups, said that an issue that Republicans “hoped would be a major weapon in turning Jews against the president was all but taken away from them.”