Nestor Kirchner, an untested provincial governor, became Argentina's president-elect by default Wednesday after former President Carlos Menem withdrew days before the national elections that opinion polls predicted he would lose by a landslide.

By law, Argentina's congress must declare Kirchner the winner by default on May 25 and he will assume office that day. But because of Menem's withdrawal, Kirchner assumes office under a cloud, having finished second in the only voting that took place. Menem won the April 27 first-round balloting, capturing 25 percent of the vote to Kirchner's 22 percent in a field of 18 candidates.

Menem's victory margin in a crowded race was insufficient to avoid what would have been Argentina's first runoff election since returning to democracy in 1983, and anti-Menem voters, polls showed, outnumbered his supporters. That left Menem, 72, for nearly two decades Argentina's dominant figure, with only a role as spoiler. He seemed to relish it.

"I say to Mr. Kirchner, he can have his 22 percent, I have the people," Menem said at an impromptu news conference. Menem said he quit because "there were not conditions for a second round" election and called the runoff "totally rigged."

In a television spot aired Wednesday, Menem declared himself a victim of political persecution. He complained that his archrival Eduardo Duhalde, Argentina's caretaker president, had manipulated the courts and congress to block a Peronist Party primary election that would have produced a single candidate to represent Argentina's dominant party. Instead, Menem, Kirchner and a third Peronist ran in the general election April 27. The results forced Menem to face Duhalde's handpicked successor in a runoff between two Peronists.

The Bush administration has praised Argentina's elections as fair and open. Kirchner, 53, said Wednesday that Menem had another reason for bowing out: He trailed by roughly 40 percent just days ahead of Sunday's vote.