Early returns in Iran's parliamentary runoff elections Friday showed conservative rivals of President Mahmoud Ahmadinejad leading in many constituencies in the vote that was billed as an endorsement of the country's controversial nuclear program.

The semiofficial Mehr news agency said the president's opponents appeared to be winning a majority of the 65 seats that were up for grabs in the second round. Official results are expected Saturday.

Ahmadinejad's conservative rivals already won an outright majority in the 290-member legislature after the first round of voting in March and the runoff was only expected to cement their victory.

Mehr said more than 5 million people voted Friday, including 1 million in the capital Tehran — the only place where Ahmadinejad supporters and opponents were in a neck-and-neck race, according to results from several polling stations.

The results suggest Ahmadinejad will face a more belligerent parliament in the remaining time of the second four-year term in office that ends August 2013.

Ahmadinejad and his wife, Aazam Farahi, cast their ballots in the afternoon without making any remarks to waiting reporters, an unusually glum appearance for the normally talkative president.

Ahmadinejad was voted in for a second term in 2009 in a hotly disputed election with the backing of the clerical establishment. But he has seen his political fortunes decline sharply after he was perceived to have defied Supreme Leader Ayatollah Ali Khamenei in April 2011 and tried to expand the authority of the presidency.

The new parliament will begin its sessions in late May. It has no direct control over major policy matters like Iran's nuclear program, but it can influence the selection of Ahmadinejad's successor and other top officials and give backing to the policies of Khamenei, who has final say on all state matters.

Iranian leaders have showcased the high voter turnout — officially, 64 percent in the first round — as a sign of trust in the clerical-led system and rejection of Western pressure over the nuclear issue.

The West suspects Iran is pursuing nuclear weapons and is demanding that Iran stop uranium enrichment. Iran has refused, saying its program is aimed at power generation and cancer treatment.

"My advice is that people take the runoff as seriously as the first round," Khamenei said in comments carried live by state television after he cast his vote.

Iran and world powers held a round of talks in April in Istanbul, the first in a year. Little progress was made beyond agreement to resume the discussions in Baghdad later this month. Iran has said it will ask the West to end or ease its sanctions, but Western nations have already rejected that.

A high voter turnout Friday would boost Iranian negotiators ahead of the talks in Baghdad, according to Ali Reza Khamesian, a political analyst in Tehran.

"Iran's leaders want to announce to the world that they have huge support from the people, and a high turnout will serve this," Khamesian said.

Of the 130 candidates, two for each of the 65 seats, 69 are conservative opponents of Ahmadinejad, about 26 favor the president and the rest are centrists. Although Ahmadinejad is likely to serve until the end of his term, his allies have been pushed out of key posts and his political clout has been weakened.

Some of the voters said they were voting over economic issues. Several rounds of U.N. sanctions over the nuclear issue have hit Iran hard, contributing to double-digit inflation and unemployment.

"In the first round I voted for those who resisted the inflation-creating policy of Ahmadinejad's administration," said Reza Behjatpour, a 20-year-old university student.