NAIROBI, Kenya (AP) — Kenyan opposition figure Raila Odinga said Tuesday he’ll challenge the results of the close presidential election with “all legal options” after Deputy President William Ruto was declared the winner, bringing new uncertainty to a country where the vote was widely considered to be its most peaceful.

Now East Africa’s most stable democracy faces weeks of disputes and the possibility that the Supreme Court will order a fresh election. Already, religious and other leaders have pleaded for calm in a country with a history of deadly post-election violence.

“Let no one take the law into their own hands,” Odinga said to his supporters.

This was his first appearance since Kenya’s electoral commission chairman on Monday declared Ruto the winner with almost 50.5% of the votes. Four of the seven commissioners abruptly announced they couldn’t support the results, and Odinga supporters scuffled with the remaining commissioners at the declaration venue.

Shortly before Odinga spoke, the four commissioners asserted to journalists that the chairman’s final math added up to 100.01% and that the excess votes would have made a “significant difference.” They also said he didn’t give them a chance to discuss the results before his declaration.

“What we saw yesterday was a travesty and blatant disregard of the constitution,” Odinga said, calling the election results “null and void.”

The 77-year-old Odinga has pursued the presidency for a quarter-century. His campaign has seven days after Monday's declaration to file a petition with the Supreme Court, which would then have 14 days to make a ruling.

The electoral commission had been widely seen as improving its transparency in this election, practically inviting Kenyans to do the tallying themselves by posting online the more than 46,000 results forms from around the country.

On Tuesday, the local Elections Observation Group announced that its highly regarded parallel voting tally “corroborates the official results” in an important check on the process.

But Odinga asserted that only the electoral commission chairman could see the final results before the declaration. “The law does not vest in the chair the powers of a dictator,” he said, and insisted that decisions by the commission must be taken by consensus.

Odinga's campaign had expected victory after outgoing President Uhuru Kenyatta in a political twist backed his former rival Odinga instead of his own deputy president.

The 55-year-old Ruto appealed to Kenyans by making the election about economic differences and not the ethnic ones that have long marked the country's politics with sometimes deadly results. He portrayed himself as an outsider from humble beginnings defying the political dynasties of Kenyatta and Odinga, whose fathers were Kenya’s first president and vice president.

Still, the turnout in last Tuesday’s vote dipped to 65% as Kenyans across the country of 56 million expressed frustration and lack of confidence that the candidates would address the problems of rising prices, high unemployment and widespread corruption. The now-wealthy Ruto himself has faced and denied multiple allegations of land grabs and other graft.

As a growing number of African leaders issued statements congratulating Ruto, Kenya's outgoing president remained silent.