"It's clear that the administration has essentially given up that possibility," he said. "I don't think it's serious any more. If you had asked me a year ago I would have said I thought it was a real possibility. I just don't think it's in the cards."
The "optimal window" for strikes would be between the November 4 election and the inauguration on January 20, 2009.
But waiting for either Barack Obama, the Democratic candidate, or his Republican opponent John McCain to be installed in the White House could preclude military action happening for the next four years or at least delay it.
An Obama victory would rule out military action by the Israelis because they would fear the consequences given the approach Obama has taken to foreign policy,"
The Iran policy of Mr McCain, whom Mr Bolton supports, was "much more realistic than the Bush administration's stance"
William Kristol, a prominent neo-conservative, told Fox News on Sunday that an Obama victory could prompt Mr Bush to launch attacks against Iran. "If the president thought John McCain was going to be the next president, he would think it more appropriate to let the next president make that decision than do it on his way out,"
A second, the official said, was to send a clear message to the United States and other countries that Israel was prepared to act militarily if diplomatic efforts to stop Iran from producing bomb-grade uranium continued to falter.
But American officials were also told that Israel had prepared plans for striking nuclear targets in Iran and could carry them out if needed.
"They are clearly nervous about this and have their air defense on guard," a Bush administration official said of the Iranians.
Two sets of advance Russian-made radar systems were recently delivered to Iran. The radar will enhance Iran's ability to detect planes flying at low altitude.
Mike McConnell, the director of national intelligence, said in February that Iran was close to acquiring Russian-produced SA-20 surface-to-air missiles. American military officials said that the deployment of such systems would hamper Israel's attack planning, putting pressure on Israel to act before the missiles are fielded.
Iran is getting nervous about aircraft fying in the air corridors adjacent to their air space. Israel is making arrangments to remove the nuclear sites in Iran.