Looking over President Obama’s evolving Iran policy over the last year, I don’t think the president and his team have gotten nearly enough credit for how they’ve calibrated an approach, especially in the wake of the June 12 elections, designed to undercut both the Iranian regime’s international and domestic propaganda, by insisting on the possibility of a deal, and the effect that his has had of exacerbating divisions among Iran’s ruling elite.

In remarks last week at the Institute for the Study of War, Gen. David Petraeus commented on these divisions, saying that while the diplomacy has intensified with Iran, the international engagement “has been complicated probably a bit just because of the preoccupation of Iran with its internal affairs.”

I mean, there are literally organizations within Iran that just, frankly, haven’t met the way they used to, certain of the important Iranian security bodies and advisory bodies that help the Supreme Leader and so forth, because — in some cases because of internal divisions among the senior members of these different groups. So that has made things more difficult, I suspect, as well.

In a late December article on the state of the administration’s engagement approach, Glenn Kessler reported the view of administration that officials that “the apparent turmoil it generated within the Iranian leadership is a useful side benefit of engagement.

The effort to engage “has had an unsettling effect on people in the regime,” one official said. “It has made it more difficult to demonize the United States and say it has been the root of all evil.”

It’s important not to overplay the extent of U.S. influence on Iran, but it’s important not to underplay it, either. We shouldn’t imagine that saying or doing X pulls a corresponding X lever in Iranian policy, but given the central place the United States occupies in the Iranian regime’s strategic and ideological perspective, there’s no doubt that U.S. policy and rhetoric have an effect.

It almost certainly had an effect during the Bush administration — a very bad one. In 2007 article, Barbara Slavin, now the foreign affairs editor of the Washington Times, wrote that Bush’s hardline policy toward Iran had had the effect of “boosting Iranian hardliners who argue that the Bush administration has no interest in reconciling with Iran and that Tehran’s best course is to reach bomb capacity as soon as possible.”

It’s no surprise, then, that U.S.-Iran talks about Iraq finally began in May this year [2007] in an atmosphere so fraught with hostility over sanctions and the nuclear issue that little has come of them. Iran, meanwhile, has refused to suspend its uranium enrichment program as demanded by U.S. Secretary of State Condoleezza Rice as a precondition for broad negotiations. A top aide to Ahmadinejad recently told me that the Iranians think Rice is lying when she says she will meet with Iran “anywhere, anytime” if Iran suspends enrichment. The Bush administration, this official said, has no interest in serious negotiations with Iran. You can hardly blame him or other Iranians for thinking this way.

President Obama deserves credit for raising doubts in the minds of a number of Iranians who think this way. He also deserves credit for resisting calls to explicitly enlist the U.S. in the Iranian opposition, which would effectively restore the “foreign stooges” propaganda tool that Iran’s hardliners are clearly desperate to have back, but that Obama’s approach has denied them. It’s been a judicious use of American power, one that recognizes the limits of America’s ability to influence events inside Iran, but also that America’s posture does have an impact on Iran’s politics.

Health care and nuclear proliferation seem to have little to do with each other. But right now the President’s ambitious nuclear non-proliferation agenda – the issue for which he received the Nobel Prize – is hanging in the balance.

Should congress fall into a state of paralysis or drastically scale back its ambition; should the health care bill get broken up and therefore eat up more of the legislative calendar; should Republican Senators continue to utilize the politics of obstruction with no political cost; and should Democrats cower in the face of this opposition – the President’s nuclear agenda, along with many other progressive priorities, will be in deep trouble. Strobe Talbott, the President of the Brookings Institution, said at a panel yesterday:

You might say what could Massachusetts possibly have to do with the arms control agenda? I think actually quite a bit. In so far as there is a partisan square-off on a lot the issues of President Obama’s agenda … the defensiveness of the Administration with regard to say health care is likely to tie over into additional difficulty with regard to other pieces of legislation, including the ratification of treaties.

The treaties that Talbott is referring to are a new Strategic Arms Reduction Treaty (START) with the Russians and the Comprehensive Test Ban Treaty (CTBT). Both of these treaties are critical to non-proliferation efforts not just on their merits, but also because these treaties demonstrate America’s seriousness about nuclear proliferation and arms reductions. 2010 is critical for the nuclear agenda, as there are two major international conferences in April and May at which the President will seek to convince other countries to do more to combat nuclear proliferation. But getting others to do more, requires the United States to actually take action and lead by example.

It is not just that the world won’t become safer if these conferences are unsuccessful, it is that the world could get a whole lot less safe. The great danger is that an unsuccessful NPT review conference, which happens every 5 years and will take place in May, could further erode states’ confidence in the non-proliferation regime, putting us closer to a cascade of nuclear proliferation. In other words, failing to act on these treaties could have really dangerous consequences.

It has long been clear that the CTBT would be particularly hard, since many GOP Senators remain bizarrely committed to the explosive testing of nuclear weapons (yes you read that write). Yet the expectation has been that ratifying a new START treaty would be relatively uncontroversial. A new START treaty has had significant bipartisan support, since it is after all an advancement of the original treaty negotiated under Ronald Reagan.

However, ratifying a new treaty would be the biggest tangible foreign policy accomplishment of President Obama’s tenure – a fact that may mobilize the Senate GOP to attempt to block any new agreement. Senate Republicans led by Jon Kyl have been making quite a bit of noise already and have been throwing out disingenuous arguments to undercut the Administration’s efforts. This seems to indicate that Senate ideologues like Kyl are looking for reasons to oppose a new deal. While there are Republican Senators, like Richard Lugar, that will in all likelihood support a START treaty, treaties need 67 votes.

Should Senate Republicans conclude that continuing to pursue a politics of obstruction and therefore blocking these critical treaties will have little if any political cost – and would alternatively offer some political gain by hurting the President – they will go nowhere and as a result so will the President’s nuclear agenda.