By Andy Sullivan
Often accused of hawkish policies, McCain told MSNBC's "Hardball" it would be difficult to convince the American people to go to war against Iran.
"I believe we can act with nations with values and principles that we hold dear and exercise enormous pressure — diplomatic, trade, financial," he said.
If he decided he had to attack, McCain said he would have to make an "even more convincing argument that it was necessary to do so because of our failure to find weapons of mass destruction" in Iraq.
"There's a little credibility gap," he said, referring to President George W. Bush, who justified the 2003 invasion of Iraq by saying it possessed weapons of mass destruction.
Iran has been a hot topic in the presidential campaign with Democrats Barack Obama and Hillary Clinton arguing that the Iraq war allowed Iran to increase its influence in southern Iraq. They also say Iranian elements have been shipping explosives across the border to attack Americans and Iraqis.
Clinton on Tuesday called Bush's Iran policy "a loser" and recommended low-level talks with a country the United States has labeled a sponsor of terrorism.
Speaking at a meeting of newspaper publishers, Clinton sought to strike a balance between the hawkish approach taken by the Bush administration and her Democratic rival Barack Obama's call for face-to-face talks with the Iranian president, who denies the Holocaust and has threatened to destroy Israel.
"The approach that the Bush administration … has neither changed behaviors or produced results," said Clinton, a former first lady who would be the first woman president.
"I've advocated both that carrot and that stick," the New York senator said, She would "try to create the beginning of lower levels of diplomatic engagement, some ongoing process."
The West accuses Iran of trying to acquire nuclear weapons under cover of a civilian program. Iran denies the charge and says it needs nuclear technology to meet electricity demand.
The United States has led international efforts to penalize Iran for failing to allay suspicions over its nuclear work.
McCain, an Arizona senator, cited published U.S. intelligence in saying that Iran appears to be close to a "tipping point" in developing the technology needed for a nuclear weapon.
He said Iran would have to be a "clear and present danger" to warrant military action and that to gain public support he would bring appropriate members of Congress to the White House for intensive consultations to show them the evidence.
The message to them would be, "I want you to be in on the takeoff as well as the landing," he said.
(Writing by Steve Holland, editing by Alan Elsner)
(To read more about the U.S. political campaign, visit Reuters "Tales from the Trail: 2008" online at http:/blogs.reuters.com/trail08/)
