President Bush met with a bipartisan group of House and Senate leaders on Tuesday to determine support for offering incentives to Iran (search) to get that nation to give up its nuclear weapons program.

The meeting on Iran's uranium enrichment (search) process occurred as the International Atomic Energy Agency (search) announced Iran's refusal of an inspection request made in January.

Publicly, the White House expressed doubt that Iran can be trusted to honor its obligations.

"We will see by their action if they are serious about living up to their international obligations. They have said that they are. We will see through their actions. You can understand why we remain skeptical," White House Press Secretary Scott McClellan said.

Iranian officials said Tuesday that they are not submitting to a second inspection of Parchin military base (search) because it's not a nuclear compound and they are not required to open it up to IAEA inspections.

U.S. officials say they think Iran has secretly conducted nuclear tests at Parchin. They add that denying the inspections does not signal cooperation with the international community despite pledges to do so.

"What the focus here is, is on Iran's behavior and Iran's efforts to develop a nuclear weapon. That's where the focus should be. And we all have a shared goal," McClellan said.

Some lawmakers meeting with the president encouraged Bush to join Europe in offering incentives to the Islamic regime in Tehran.

"I think he has to embrace that and they have to embrace the fact that there have to be sticks and not just carrots," said Sen. Joe Biden, D-Del., ranking Democrat on the Senate Foreign Relations Committee.

But Biden said he's not totally optimistic that such a strategy would work.

"Even if the Europeans and Americans are on the exact same page, we do everything right, there's still a 50 percent chance for this to work, but we've got to try it," he said.

Experts on Iran say it's not just the mullahs running the country who desire nuclear weapons. It's a national objective shared by many elements of Iranian society. Iran sits in a tough regional neighborhood with a nuclear-armed Pakistan on one border and about 165,000 U.S. troops in bordering Iraq and Afghanistan.

Iran and Israel have been technically at odds for decades. Israel is widely believed to have nuclear weapons, though it has never said so specifically.

"I think the Iranians do intend to take their nuclear program to the point of threshold nuclear capability, and I think it will be very hard to convince them otherwise," said former U.S. ambassador to Israel Martin Indyk.

Like Biden, Indyk said Europe and the United States have to try several approaches to dealing with Iran, including turning up the heat while pouring on the sweet.

"That's got to be the tradeoff there. Sweeter carrots for bigger sticks," he said.

The White House says the president has not yet decided whether to endorse the European incentives. Lawmakers said they got the impression he's leaning toward doing so.

Click in the box near the top of the story to watch a report by FOX News' Wendell Goler.