"We prefer to resolve this diplomatically, and there is still time to do so," Obama said.

The president said, however, that "all options are on the table."

The USA Today newspaper reports some experts believe Iran's nuclear program is too far along to prevent it from becoming militarized.

Meanwhile, Iran is seeking a diplomatic deal that allows it to keep a nuclear program it says is for medical and research purposes.

Does U.S. Rep. Steve King, R-Iowa, think the United States will be at war with Iran, or can American officials and other nations use effectively use diplomacy to stifle the nuclear ambitions of Iranian President Mahmoud Ahmadinejad?

"I don't think that Ahmadinejad can be talked out of this," King said in an interview this week with The Daily Times Herald and Jefferson Bee & Herald.

Does King believe the United States will be in a ground conflict with Iran?

"No, I don't think so," King said. "I think that there's a reasonable chance that there can be a regime change brought about in Iran, and I say that because of some of the people that I sit down with in closed doors and have these conversations that know that country."

Without regime change, "this comes to a head," King said.

"I don't think it's going to be a ground campaign," King said. "I think it will be more like an air strike or a series of them if it comes to that. Anybody in this business should do everything possible to avert this."

King said it is clear Iran will not be subject to the Cold War-era "mutually assured destruction strategy" that retrained the Soviet Union for a half century.

"It is a very, very difficult foreign-policy problem that we have," King said. "I didn't think George (W.) Bush was aggressive enough in his push on this."

The Kiron congressman said Israel is a good indicator of what type of decision should be made - and when - with regard to Iran's nuclear development.

"They have a lot more at stake," King said of Israel. "They are the first likely target."

King said that if he were president, he would back-channel message Ahmadinejad - probably through the Swiss - with a line-in-the-sand demand for abandonment of Iranian nuclear pursuits.

"If I am the guy making the call, say in the White House, it would be this message: I would place an 'X' on the calendar that designates the date beyond which you will not be able to continue your nuclear endeavor," King said. "You don't know that date, but I do. And I'm going to keep my word on this all the way through, and that is you'll not be allowed to develop a nuclear device and a means to develop it. It will come to an end."

King stresses that he would seek to work with Iran diplomatically and provide Ahmadinejad with a way to save political face with his people.

"That message would have to be delivered firmly and cleanly - and you can't be bluffing," King said. "Right now, we've been played by the Iranians."