UPDATE 1-Obama says won't guarantee Ahmadinejad a meeting

(Adds McCain campaign comment, more Obama comments)

By Caren Bohan

LAS CRUCES, New Mexico, May 26 (Reuters) - Democrat Barack Obama underscored his willingness to talk to leaders of countries like Iran that are considered U.S. adversaries but said on Monday that does not necessarily mean an audience with Iranian President Mahmoud Ahmadinejad.

Obama, the Democratic Party front-runner vying to face Republican Sen. John McCain in the November race for the White House, has said he was willing to meet with leaders of countries such as Iran, Syria, Cuba and Venezuela without preconditions.

McCain has criticized that view, saying that sitting down with someone like Ahmadinejad would give the Iranian president a spotlight and send the wrong signal to U.S. allies such as Israel.

Iran does not recognize Israel's existence and Ahmadinejad has called the country a "stinking corpse."

Obama, an Illinois senator, said Iranian presidential elections in 2009 would be a factor in the timing of any meetings, as would considerations of who wields the power.

"There's no reason why we would necessarily meet with Ahmadinejad before we know that he was actually in power. He's not the most powerful person in Iran," Obama told reporters while campaigning in New Mexico.

Under Iran's system of clerical rule, the Islamic Republic's religious establishment has final say in all state matters.

The McCain campaign accused Obama of backtracking.

"Over the past year, Sen. Obama has repeatedly confirmed that he'd meet unconditionally with Ahmadinejad and the leaders of Syria, Cuba and Venezuela," said McCain spokesman Brian Rogers.

Republicans have accused Obama of inconsistency on his policy on talking to adversaries. In recent weeks, Obama and his aides have emphasized that, while there would be no "preconditions" for potential top-level meetings, there would be extensive staff-level preparations.

In the case of Iran, Obama said, "Preparation means that there are low-level talks in which there's clarity about our concerns around the nuclear weapons program but that we're willing to listen to their perspective."

Obama said his position has been consistent.

"I've said that with sufficient preparation I would be happy to meet leaders from other sovereign states including countries like Iran or North Korea or Venezuela," he said. "I have said that it is important to make sure that it begins with low-level diplomatic engagement and that there's a clear agenda so that any meetings would be constructive." (Editing by Doina Chiacu) (For more about the U.S. political campaign, visit Reuters "Tales from the Trail: 2008" online at blogs.reuters.com/trail08/)