President Boris Yeltsin and his foes in the State Duma formed an unlikely alliance Wednesday, forcing through the first reading of a law on Duma elections.


The emphatic decision, with 258 of 450 deputies voting in favor, gave the lower house of parliament a foundation in law for the first time -- almost a year after the Duma was voted into life last December.


At the same time, as deputies backed the draft law put to them by Yeltsin, they threw out an alternative electoral code drawn up by Grigory Yavlinsky's liberal Yabloko faction.


The key breakthrough in the battle of the drafts came when Yeltsin won the support of his old foe Vladimir Isakov, the communist chairman of the Duma's legislative committee. Isakov threw his weight behind the president's draft Tuesday while putting forward several amendments of his own.


Yeltsin's electoral law roughly follows the same lines as the improvised system set up for last December's elections, with some changes.


The Duma backed two of Isakov's amendments, which keep the law even closer to the original prototype. The first preserves the balance of deputies: 225 will be elected in single-member constituencies and 225 will be chosen from national party lists. Yeltsin had proposed tilting the balance toward the constituencies, a move that would have undermined the party structures in the Duma. The second amendment preserves candidates' right to run both on party lists and in constituencies, giving them two chances to make it into parliament.


By backing Yeltsin's drafts, deputies said they were securing their immediate future against all eventualities.


"According to the constitution the Duma can soon be dissolved," said Sergei Zenkin, the legislative committee's specialist, in an interview. "It's our job to be prepared for this situation. We want the law on elections to be adopted as soon as possible. It would be shameful not to pass the law and repeat the last year's situation, when the election laws were approved only by the president."


The rules of the December 1993 elections were set by presidential decree and changed several times during the campaign itself.


Yavlinsky spoke up passionately for his faction's detailed electoral code, which was drawn up by a group of 20 experts. He chided legislators for being too hasty in adopting a historic law.


"This law is almost the only thing for which we will be remembered," Yavlinsky told the chamber.


Yavlinsky said his draft code defended voters against "pressure from local administrations and big money," whereas Yeltsin's draft law was too vague, and open to abuse.


"I remind you of Stalin's old formula, 'It's not important who wins the elections, it's important who counts them,'" Yavlinsky said.


Later, the chamber rejected two draft laws on holding national referenda, although the president's version won wide backing.The president's and Yavlinsky's draft referendum laws have key differences. Yeltsin's rules out putting a question in a referendum on pre-term elections, but not on putting back elections. This leaves hope for the speaker of the upper house of parliament, Vladimir Shumeiko, who has called for a referendum on postponing parliamentary elections, due in December 1995.


Yavlinsky's draft law is much stricter, and rules out referendums on both these questions. Yavlinsky said his draft was designed to stop a referendum being used as a "political weapon."


In both drafts, a petition of 2 million signatures is required before a question can be put to a national referendum. The Communist Party has been busy for the past few months collecting a million signatures, as stipulated by the old law, to call for a referendum on early presidential elections.


Yavlinsky's group has also drawn up a draft law on presidential elections that requires all candidates to have a medical certificate proving their "physical and psychological health" and contains a statement on their earnings over the preceding four years.