Iranian reformists urged their supporters to rally behind moderate cleric Akbar Hashemi Rafsanjani to prevent his surprise hard-line challenger Mahmoud Ahmadinejad from winning a presidential run-off.
"We should use our full force to defend Rafsanjani. We should form an anti-fascist front," said Hamid Reza Jalalipour, a leader of the reformist Islamic Iran Participation Front.
Similarly, backers of Tehran ex-mayor Ahmadinejad urged conservatives to unite in support of the man who stunned Iran by almost overhauling elder statesman Rafsanjani in Friday's first-round vote.
The hard-line Siyasat-e-Ruznewspaper said conservatives could have won outright if they had settled on one candidate. "However it is not late now and there is just one step to victory ... Unity must be at the top of our agenda," it said.
Rafsanjani and Ahmadinejad, with about one fifth of the vote each, just pulled clear of their five rivals in a poll damned by Washington as a travesty of the democracy Iranians yearned for.
"I just don't see the Iranian elections as being a serious attempt to move Iran closer to a democratic future," Secretary of State Condoleezza Rice told Fox News television in Jerusalem.
She criticized the legitimacy of the electoral process, in which unelected clerics barred most of the 1,000 presidential hopefuls, including all the women, from standing.
Those defects prompted some Iranian reformists, including Nobel Peace Prize winner Shirin Ebadi, to boycott the poll.
"As long as they (the clerical establishment) decide for people and tell people whom to vote for by qualifying and disqualifying candidates, I will not vote," she said.
Supreme Leader Ayatollah Ali Khamenei hailed the 63 percent turnout as a slap to "ignorant enemy" President Bush.
Iranians now face a stark choice on their country's future in the first run-off election since the 1979 Islamic revolution.
A senior Rafsanjani aide urged reformists, secularists and moderate conservatives to unite behind the former president to maintain a political balance against "militarist" tendencies.
"We all can hear the footsteps of fascism," Mohammad Atrianfar told Reuters. "If we create a united front for a national coalition, we will win the Friday election."
He echoed accusations from Moin's camp that Ahmadinejad had used Basij religious militiamen to help get out the vote.
"Using a paramilitary organization to mobilize voters is a very dangerous move," Atrianfar said.
The daily Sharq, which Atrianfar controls, said voting for Rafsanjani was the only way to stop religious hard-liners from gaining a monopoly on Iran's ruling institutions.
"We can call him arrogant and criticize his preference for development over democracy," wrote columnist Mohammad Qouchani, but added: "Now we clearly see that Rafsanjani is the only choice left for preserving democracy in Iran."
Though Rafsanjani does not challenge clerical rule, he is seen as a counterweight to the hard-line anti-Western elite and has called for a "new chapter" in Iran-US relations.
Ahmadinejad, linked to the Basij and Revolutionary Guards, has said talks with Washington will not solve Iran's ills.
Young Basijis, waving green and black flags, celebrated his success late into the night, driving pickup trucks around the Tehran parks where reformists had held wild campaign rallies.
While Rafsanjani, 70, has promised to improve ties with the West and preserve social freedoms, his 49-year-old opponent has focused on tackling poverty and maintaining Islamic values.
"My government will support the poor and the deprived," Ahmadinejad said after his first-round victory.
Their contest could reopen the social rifts in Iran exposed by the closest election since the Islamic revolution.
Third-placed reformist cleric Mehdi Karroubi's main campaign pledge was to give everyone over 18 a monthly $62 state handout.
"The result of the election proved that political parties and certain media leaders cannot understand the country's social mainstream and ... social realities," the hard-line daily Keyhansaid.