The controversial outcome of Iran's presidential election has prompted a potentially explosive political crisis. Post-election fights have erupted in the streets and in the corridors of power in Tehran that are the continuation of a bitter political campaign.

The government declared the incumbent, President Mahmoud Ahmadinejad, the winner in a landslide over his closest challenger, reformist Mir Hossein Mousavi. That sparked charges of a rigged election and violent street protests by angry Mousavi supporters.  

But analysts say there is also a fight going on behind the scenes that reflects political splits that came out into the open during the election campaign.

During the campaign, the president accused Mousavi of accepting support from corrupt elements, and specifically named former President Ali Akbar Hashemi Rafsanjani as the prime backer. Mousavi accused the incumbent of bad judgment and bringing the country into disrepute internationally.

Reva Bhalla, an Iranian affairs analyst with the private intelligence firm Stratfor, says President Ahmadinejad may feel his re-election means it is payback time for the personal attacks.

"I think it definitely emboldens him," said Reva Bhalla. "And I think we've already seen that already come to light where we've seen mass arrests and basically this whole agenda to uproot his opponents. And that's exactly why very senior members of the regime like [former President Ali Akbar Hashemi] Rafsanjani and [Parliamentary Speaker Ali] Larijani are pretty concerned right now and are appealing to the Supreme Leader to make sure that that doesn't happen."

Supreme Leader Ali Khamenei gave tacit backing to the president during the campaign, and welcomed the election results, calling them a divine assessment. But faced with street protests and objections from Mousavi and other political figures, he abruptly ordered the powerful Guardian Council - comprised of 12 Islamic clerics - to investigate voter fraud. It is an unprecedented move after an election campaign that was unprecedented in several ways.

Alex Vatanka, senior Middle East analyst of Jane's Information Group, says Ayatollah Khamenei's decision reflects the continuing struggle between the incumbent president and the still-powerful former President Rafsanjani that surfaced in the campaign.

"How can you go after pillars of the Islamic Republic like Rafsanjani, who still hold significant positions within the system, and expect that he's not going to bite back when you accuse him and his entire family? This is the misreading, this is the big gamble of Khamenei," said Alex Vatanka. "I wonder if his u-turn is actually a reflection of what he's actually gone and done - supporting Ahmadinejad the way he has done. It's a huge fight."

But are the vote fraud allegations true? There is no transparency in ballot counting and no exit polls. The only independent public opinion survey, taken three weeks before the election by the New America Foundation and Terror Free Tomorrow, shows that the president could have won by the margin claimed.

But Ken Ballen of Terror Free Tomorrow says there is no way to know for sure.

"We have the only independent poll out there," he said. "And it was early, it was three weeks before the election. There could have been a surge for Mousavi that is not reflected in our polling numbers. And I'm not saying that the election was free and fair. There are a lot of indications that it wasn't. But there is a difference between whether the election was free and fair, and whether the majority of the people support Ahmadinejad."

In fact the president has portrayed himself as a populist - as he did when he unexpectedly beat Rafsanjani in 2005 - and analysts say he maintains a strong base of support in rural areas and among the poor. In contrast, says Ballen, Mousavi's supporters come from the other end of Iran's economic spectrum.

The only groups that we found in our poll three weeks before the election - again, I make that caveat - but the only groups that we found supporting Mousavi or where he was competitive with Ahmadinejad were university students, university graduates, and the highest income Iranians. So the protests are now occurring in Tehran. I don't know if they reflect the will of the whole country.

It is not clear whether the protests, which have been reported in other locales like Shiraz, will be sustained.

Analyst Alex Vatanka says these demonstrations have organization and backing from disgruntled politicians in the ruling elite, and will end only if they decide to concede to President Ahmadinejad.

"I think that there's such an anger right now that they are going to stay in the streets," said Vatanka. "The only thing that's going to make this thing go away quickly is if - and that's a big 'if,' and that's thanks to Ahmadinejad - if the top echelons of the Islamic Republic, people like Rafsanjani, Mousavi, [former President Mohammad] Khatami, decide that they're going to walk away from this fight."

But even if the protests end, analysts say, the rancor and bitterness that came out during the campaign is likely to linger.