As U.S. officials seek a diplomatic solution to the Iranian regime's suspected nuclear weapons program, a growing chorus of critics on the right say the Bush administration is being soft on Iran and other so-called "enemies of freedom."

These critics, including some members of the U.S. Congress, say the administration's diplomatic strategy with Iran will likely come to naught and a more aggressive approach — including economic sanctions and regime change — should be pursued.

"Time after time, the regime in Tehran has defied the world's demands that it abandon it nuclear ambitions, even heralding its successful production of enriched uranium only a few months ago," said Rep. Ileana Ros-Lehtinen, chairwoman of the House International Relations Subcommittee on the Middle East and Central Asia.

FOX Fan Speakout: What do YOU think? Is it time to get tough on Iran?

Ros-Lehtinen made those remarks shortly after Secretary of State Condoleezza Rice announced in May that the United States would engage in direct talks with the Iranian regime if it agreed to suspend its nuclear enrichment program — a proposal the Iranian government has so far rejected.

CountryWatch: Iran

The Florida Republican is chief sponsor of the Iran Freedom Support Act, which calls for tougher U.S. sanctions on Iran until the government there "has verifiably dismantled its weapons of mass destruction programs" and encourages the president to acquire U.N. Security Council approval for tougher global sanctions.

Although the bill does not specifically call for "regime change," it funds assistance to human rights and opposition groups seeking to employ democracy-building efforts aimed at undoing the Iranian regime.

"This bill has a short-term and long-term approach built into one. In the short term, deny regime resources to engage in destructive behavior and weaken regime, while supporting and strengthening pro-democracy opposition in Iran which is a long-term, more permanent solution to the threats posed by regime in Iran," Ros-Lehtinen told FOXNews.com by e-mail.

"These most go hand in hand if opposition is to have a real chance and, most importantly, if we're going to prevent Iran threat from escalating further," she said.

The bill passed the House in April and now sits in the Senate Foreign Relations Committee. Sen. Rick Santorum, R-Pa., is the chief sponsor in the Senate, where the measure has 60 co-sponsors.

While the legislative approach calls for a tough, proactive approach by the United States, some critics outside Congress want to go even further, saying the administration has been too soft on Iran and in its handling of the War on Terror.

"They've been killing us for 27 years and we have yet to respond … [the administration] is not ready to take on Iran," said Michael Ledeen, author of "The War Against the Terror Masters: Why It Happened. Where We Are Now. How We'll Win."

Ledeen, a Middle East scholar with the American Enterprise Institute, is not shy about his interest in toppling the Shiite clerical regime in Iran. He said he is frustrated that the Bush administration seems unwilling to take the fight to Iran — as well as Syria — where the U.S. military should be destroying brazen terror camps just over the Iraqi borders.

"The administration lacks the will to do it," he told FOXNews.com. "They would rather be in a nice negotiating room in Europe with the likes of (former British foreign secretary) Jack Straw."

Critics like Ledeen say they are frustrated by what they see as lost opportunities to take down the Iranian and Syrian regimes and win the global War on Terror. They say military strikes against Iranian nuclear targets are a last resort, but should still be a realistic option.

But others say these critics, defined as members of the "neoconservative" wing of the Republican Party and the base of President Bush's foreign policy support, lost their credibility when they pushed for a war against Iraq that has so far been marred by increased sectarian violence and an ongoing insurgency that has killed more than 2,500 U.S. soldiers and thousands more Iraqi civilians.

"The question we should ask the neoconservatives is why should we listen to you?" said conservative military analyst Bill Lind, adding that he believes many in the neoconservative camp ultimately favor military action against Iran.

"That would be catastrophic for the United States, just like it has been in Iraq," Lind said.

“Michael (Ledeen) seems to be ignoring the reality … the administration is a little busy in Iraq,” said Charles Pena, author of "Winning the Un-War: A New Strategy for the War on Terrorism."

Pena said it is unclear how much of a real threat Iran is to the United States — and while it may be a continuing threat to Israel, thanks to their own nuclear aresenal, Israel can take care of itself.

“It comes down to this — [the Iranians] don’t have the military capability to threaten us even if they acquire nuclear capability,” said Pena. “We ought not engage in military action.”

Like the State Department, the hawks pushing for more intervention call Iran and regional neighbor Syria state sponsors of terror, and tick off a number of connected groups, like Hezbollah, Hamas and even Al Qaeda, as threats to the United States and Israel.

They say reshaping and democratization in the Middle East is the only way to stabilize the region, and Iraq was and is a part of that strategy. The president and his team now must do more to stop the other threats.

"The White House doesn't understand that the Iranians need us more than we need the Iranians," said Michael Rubin, an AEI scholar and former consultant to the Coalition Provisional Authority in Iraq.

The administration needs to be brandishing more sticks than carrots for the Iranian regime, he said. "The biggest carrot we can give them is to sit down and talk with them directly … giving them legitimacy.”

Rubin added that Secretary of State Condoleezza Rice blew U.S. chances to bolster the anti-Syrian revolution in Lebanon when she met with Lebanon's pro-Syrian President Emile Lahoud last summer.

The so-called "Cedar Revolution" in Lebanon in 2005 has fizzled, Rubin said, in part because the United States did not vigorously support pro-democracy groups over Syrian sympathizers, like Hezbollah, which has a strong presence in the elected government there.

While Rice did not meet with Lahoud in a second trip in February, Rubin said by then the message was already sent that the Americans were not serious about supporting revolution there.

"Her willingness to subvert principal to diplomatic convention single-handedly deflated the democracy movement in Lebanon," he said.

On the other hand, the Bush administration imposed economic sanctions on Syria on May 6. Bush said the Syrian government is a threat to Lebanon's independence, is pursuing weapons of mass destruction and is undermining stabilization and reconstruction of Iraq.

On Wednesday, Bush restated that the Iranians must suspend their uranium enrichment activities before the United States will negotiate elements of a package of incentives offered by the five permanent members of the U.N. Security Council plus Germany.

"We'll come to the table to negotiate, so long as the Iranians verifiably end any enrichment activities. The Iranians have said that they will end Iranian enrichment activities before. ... We're just asking them to do what they already said they would do," Bush said at an annual summit of the European Union and United States.

"But it's their choice to make. And I'm convinced that when they look and see that we're working very closely together, that they will see the seriousness of our intent to resolve this in a diplomatic and peaceful way," he said.

Iranian officials said Wednesday they will wait until August to comment on the incentives package. Meanwhile, Tehran claims U.S. insistence that Tehran suspend its activities makes it unlikely the two nations will hold talks or reach a solution. That outcome doesn't surprise opponents of that regime.

"Direct talks with Iran and offering a package of incentives is a bad idea and would only be interpreted as a sign of weakness by Tehran," said Alireza Jafarzadeh, founder of Strategic Policy Consulting, Inc., and former spokesman for the National Council for the Resistance of Iran, labeled a terror organization by the State Department but warmly received by Ros-Lehtinen and others on Capitol Hill.

Rather than approaching Tehran through the United Nations, the administration should be supporting regime change through labor unions and other active democracy movements in Iran, particularly by arming them with tools for communication and organization, he said.

“(Iranian President Mahmoud) Ahmadinejad is facing major problems domestically, as the Iranian people have stepped up their anti-government demonstrations and protest acts,” Jafarzadeh said, adding that diplomacy is “a dead horse.”

“Regime change is the only viable and the most realistic option to ends the threat of the turbaned tyrants inside Iran and abroad,” Jafarzadeh added.

Critics of the neoconservative formula say no matter how much ordinary Iranians are unhappy with the mullahs, any American attempt at regime change and military intervention will spark fierce nationalism in that country.

Besides, the clerics have amassed Iranian martyrs ready to fight, and anything seen as another U.S. invasion in the region would touch off festering Islamic resistance movements in nations like Saudi Arabia, Bahrain and even Kuwait. It would find sympathy from Shiites in Iraq and even Sunni Muslims in the region who see U.S. intervention as a greater threat than the religious differences among sects, say some analysts.

“These people don’t have the foggiest of the Middle East,” Tony Sullivan, an Arabist and president of Near East Support Services, a private consulting service dealing with the Middle East, said of the hawks.

Striking Iran “would be the greatest threat to the defense and promotion of U.S. national interests that I could think of,” Sullivan said. While Bush could “eviscerate" Syria, “Iran has enormous proxies in Iraq, the Gulf oil fields … Iran is in a position to explode the entire Middle East the first time a bomb drops.”

“People made that same argument with Afghanistan and Iraq. It didn’t happen,” countered Rubin.

He noted that he supports trying everything before the military option because of the "high costs" in other areas. “But if it means Iran having a nuclear weapon, it’s not much of a choice,” Rubin said.

Ledeen dismisses talk that the Iranians have not yet attacked U.S. interests directly, saying Tehran has been covertly aiding terrorists who are attacking U.S. soldiers in Iraq.

“We also know from abundant evidence … of the intimate working relationships between terrorists in Iraq and the regimes in Tehran and (the Syrian capital of) Damascus,” Ledeen told the House committee in March.

Meanwhile, Santorum, who sponsored the Senate legislation calling for a tougher approach, is willing to support the president's actions so far, said his spokesman Robert Traynham.

“The senator thinks the administration is approaching this with the right balance, with tough talk by the secretary of state and by the president ... and going through diplomatic channels to get the regime to change.”

Pena warned that it is naive to think hawkish conservative voices are only on the outside of the administration, trying to push it toward a more aggressive foreign policy in the Middle East. Rather, the administration is using its supporters to whip up this sentiment while it plays out the diplomatic card in the United Nations.

"It's just what happened in Iraq — first, you get AEI and the media to start beating the drums" for war, said Pena. "I think the fact that the voices are getting a little louder is an indication of where the administration is likely to move."