NAIROBI, Kenya (AP) — A U.S. congressional delegation has arrived in Kenya to meet with the new president-elect and the opposition figure likely to file a court challenge to his election loss in the latest electoral crisis for East Africa’s most stable democracy.

The new U.S. ambassador to Kenya, Meg Whitman, said the delegation led by Sen. Chris Coons also will meet with outgoing Kenyan President Uhuru Kenyatta, who has been publicly silent since the Aug. 9 election.

President-elect William Ruto is Kenyatta’s deputy president, but the two fell out years ago, and Kenyatta in the election backed longtime opposition figure Raila Odinga instead.

Odinga has said he is exploring “all constitutional and legal options” to challenge his close election loss. His campaign has a week from Monday’s declaration of Ruto’s win to go to the Supreme Court, which then has 14 days to rule.

Kenya's electoral commission publicly split in chaos just minutes before Monday's declaration, with commissioners accusing each other of misconduct.

The transition in Kenya will have significant impact on the East Africa region, where Kenyatta had been working with the U.S. to try to mediate in Ethiopia's Tigray conflict and promoting peace efforts between Rwanda and Congo.