Famed for his political cunning and Cheshire cat grin, Ali Akbar Hashemi Rafsanjani is on the verge of a political comeback.

Rafsanjani, who dominated Iranian politics for 16 years and tried to improve relations with the United States through a secret arms deal and a lucrative oil development offer, is now the leading candidate to become Iran's next president, according to Iranian politicians and analysts.

The election is not until May 13, but the backroom intrigue at the core of Iranian politics has already begun to shape the race as the two main political blocs struggle to settle on candidates. Odds that Rafsanjani, who served two terms as president, will run again are now at "more than 50 percent," Mohammed Hashemi, his brother, said in an interview.

The main question is, can Rafsanjani win? Iran's political environment has changed dramatically since he served as speaker of parliament in the 1980s and as president from 1989 to 1997.

An ayatollah who advocates free markets, Rafsanjani was once the face of moderation in Iran. He persuaded the leader of the Islamic revolution, Ayatollah Ruhollah Khomeini, to end the war with Iraq in 1988. In the 1990s, he oversaw the period after the war, which included Khomeini's abrupt death, and opened up the rigid country. Along with privatization, his government revived the shah's stock market. Beethoven and Arthur Miller's "The Crucible" were performed in Tehran theaters. And women began to wear nail polish in public and even show a bit of hair from under their scarves.

Rafsanjani tempered the policy to avoid "Westoxication" -- or poisoning from the West -- by improving ties with Europe and making overtures to the United States. As speaker, he orchestrated the secret arms-for-hostages deal with the Reagan administration. During the Clinton years, he offered Conoco the biggest joint oil development venture in Iranian history; the deal was aborted when the United States slapped new sanctions on Iranian oil dealings with U.S. companies.

But Rafsanjani was succeeded by a new bloc of reformers led by President Mohammad Khatami, a dark horse whose landslide victory in 1997 transformed Iranian politics. If Rafsanjani decides to run, he would be considered a conservative candidate.

"Politics in Iran are always evolving," said Hadi Semati, a Tehran University political scientist now at the Carnegie Endowment for International Peace in Washington.

Another run for the presidency by Rafsanjani would be a monumental resurrection, one that Iranian analysts compare to Richard Nixon's comeback after he lost bids for the presidency and the California governorship. His supporters floated the idea in 1997 of amending the constitutional limit of two terms so he could run again, but the idea was shot down by a public that felt betrayed by his failure to rebuild Iran's economy and by corruption linked to his government and family, analysts say. Backers say he could run again because the constitution limits three consecutive terms -- not a third term.

Rafsanjani tried a comeback in 2000 parliamentary elections but failed to win enough votes for any of the 30 seats from Tehran. Only when Iran's supreme leader ordered a recount did he place 29th, but the manipulation was so transparent that he declined the seat.

Rafsanjani, who declined an interview request, has not been totally sidelined. After the presidency, he headed the Expediency Council, a body that weighs in during deadlocks between parliament and the Guardian Council, the clerical panel that can veto legislation as well as disqualify candidates for public office. Despite the lofty title, the job is not on the political front line.

Iranian politicians and analysts say Rafsanjani, 70, is fixated on rebuilding his legacy.

"He has an historic paradigm in mind: Prime Minister Amir Kabir from the Qajar dynasty, who modernized Iran and has a very positive place in Iranian history," said Amir Mohebian, political editor of the conservative Resalat newspaper, referring to a 19th-century figure. "That's why he came to politics. As president, he declared a program promising his reconstruction program would provide progress. But after he left the presidency, both left and right saw that little happened. So he needs to come back to politics to save this program, to restore his place in history."

Rafsanjani faces little competition, so far, from reformers. A dramatic shift in the balance of power over the past 18 months has brought conservatives to power in parliament and on Tehran's influential city council.

Reza Khatami, the president's younger brother and a former member of parliament, is widely viewed as the strongest reformist candidate. But the public is deeply disillusioned with the reformers' failure to enact democratic changes, analysts say.

Plus, the Guardian Council disqualified Reza Khatami -- as well as more than 80 other reformist incumbents -- from running for parliament again in February elections, a move that diminishes the odds of winning approval to run for the presidency, analysts say.

"The conservatives can win, but only by disqualifying all rivals. If they can, they will try to accept only people nobody knows," said Mohsen Mirdamadi, a former member of parliament and one of those disqualified from running.

A former parliamentary speaker, Mehdi Karrubi, and a former education minister, Mustafa Moin, are considered likely reformist candidates, politicians say.

Among conservatives, the other contenders so far are: Ali Akbar Velayati, a former foreign minister; Ali Larijani, a former state broadcasting chief; Mahmoud Ahmadi-Nejad, the mayor of Tehran; Gholam Ali Haddad-Adel, the speaker of parliament; Ahmad Tavakoli, a parliamentarian; and Mohsen Rezaie, a former Revolutionary Guards commander.

The most strident conservatives, who this year won the most seats in parliament, appear to prefer candidates other than Rafsanjani. "We believe the Expediency Council is a very suitable place for him," said Hossein Shariatmadari, a leading conservative thinker and editor of the Kayhan newspaper.

Rafsanjani's biggest obstacle may be his record. "I haven't met anyone who says anything good about him," a Western diplomat who monitors Iranian politics said on condition of anonymity.

Rafsanjani's brother, Hashemi, said initial polls strongly favored the former president. "In the last poll, he had about 60 percent -- with a big gap between him and the next, who had 10 or 11 percent," he said.

Iran, however, is traditionally fickle about its politicians. On the eve of the reformers' victory eight years ago, the conservative candidate was expected to sweep to victory.

"Sometimes the polls are wrong," Hashemi conceded. "It doesn't happen only in the U.S."

Ali Akbar Hashemi Rafsanjani served as parliament speaker in the 1980s and as president from 1989 to 1997.