The two Egyptian presidential candidates who will compete in a runoff after a landmark election this past week sought Saturday to portray themselves as champions of last year’s popular revolt, while losing candidates called for a recount and suggested that fraud may have altered the outcome.

Leftist candidate Hamdeen Sabbahi, who finished third, said he would file a lawsuit asking that the June 16-17 runoff be suspended because of what he called irregularities and a pending legal case against former prime minister Ahmed Shafiq, one of the contenders who remains in the race. Sabbahi said during a news conference Saturday that “all indications confirm” that Sabbahi should have made the runoff.

Sabbahi and former Arab League chief Amr Moussa, another losing candidate, called for a probe into allegations that 900,000 policemen and soldiers unlawfully received voter registration cards, a violation they contend could have given Shafiq his edge. Members of Egypt’s security forces are barred from voting.

The allegations of fraud underscored how contentious the runoff period is likely to be as Muslim Brotherhood candidate Mohammed Morsi and Shafiq face off. Both are expected to court the vote of supporters of last year’s revolution, many of whom were disappointed by the results of the first round.

The Brotherhood moved Saturday to woo the other top vote-getters in hopes of broadening its constituency for the runoff. But none of the contenders who lost agreed to endorse him or attend a meeting that the Brotherhood convened. Morsi, whose group was slow to embrace the revolt, billed his candidacy as the best shot to keep the revolutionary spirit alive.

“We are certain that the runoff will go in the revolution’s favor,” he said at a news conference Saturday night.

Shafiq held a news conference earlier in the day in which he sought to dispel the notion that he would govern with the same ruthlessness as his former boss, ousted president Hosni Mubarak. As a candidate, Shafiq had promised that if elected, he would thwart the growing influence of Islamists and restore order, themes reminiscent of the priorities of Mubarak’s authoritarian rule.

“We all sought to achieve for Egypt a democracy it thirsted for,” Shafiq told reporters Saturday. “Our visions differed, our methods varied. That is the nature of democracy.”

The preliminary vote tally that put Morsi and Shafiq ahead of the pack of 13 candidates was based on reports from state media. Formal results are to be announced Tuesday.

Meanwhile, former U.S. president Jimmy Carter, whose organization monitored the election Wednesday and Thursday, said his team faced restrictions that made a comprehensive assessment of the vote impossible.

“Usually we go wherever we wish and arrive several weeks ahead of time, but that was not the case this time,” he told reporters in Cairo on Saturday, complaining that his observers received credentials just a few days before the vote.

Carter also lamented that international monitors were limited to spending no more than 30 minutes at each polling station and were not given access to electoral centers where the votes were tallied. He did not suggest, however, that the election had been invalidated.

“There were many violations, and each violation was serious, but collectively they did not violate the integrity of the elections as a whole,” he said.

Correspondent Leila Fadel contributed to this report.