The most common theory about why President Obama seems reluctant to negotiate seriously with Iran is that a presidential campaign is no time for serious negotiations. If Obama makes concessions--and concessions, after all, are part of serious negotiation--he'll be accused of appeasement by Mitt Romney and a flock of right-wing hawks.
Flynt Leverett and Hillary Mann Leverett are now advancing a second theory: the administration's plan isn't just to get through the election without conducting serious negotiations--after which, according to the standard theory, talks with Iran can begin in earnest; no, the plan is to get through eternity without conducting serious negotiations:
In reality, [Obama's] administration is "buying time" for a more pernicious agenda: time for covert action to sabotage Tehran's nuclear program; time for sanctions to set the stage for regime change in Iran; and time for the United States, its European and Sunni Arab partners, and Turkey to weaken the Islamic Republic by overthrowing the Assad government in Syria.
The Leveretts, who served in the Bush administration, are Iran experts with good connections to people in the Iranian government. Indeed, they've drawn fire from neoconservatives who claim their proximity to Iranian officials has left them too sympathetic to the regime.
My own view is that there is currently a dangerous shortage of people trying to help us understand how the world looks from Iran's point of view (a kind of understanding that typically abets successful negotiation, even if that's a moot point for now). And in this case I think the Leveretts have performed a particularly valuable service, because, whether or not the Obama administration really is angling for regime change, you can see, after reading their article, how the Iranian regime would think that's the administration's goal.