Former Foreign Minister Raffi Hovannisian, the top challenger in Monday's presidential election in Armenia, called on supporters to rally this weekend to protest the reported outcome of the vote, reports Radio Free Europe/Radio Liberty.
Thousands of demonstrators gathered in Yerevan to protest the results, which show in a preliminary tally that incumbent President Serzh Sargsyan secured the majority of the vote.
The European Union and members of an international observer mission expressed concern about the conduct of the election.
U.S. State Department spokeswoman Victoria Nuland issued a statement saying Washington shared concerns over the role of the Sargsyan's ruling party during the campaign.
"We agree with the findings that while Election Day was calm and orderly, it was marked by undue interference in the process, mainly by proxies representing the incumbent, and some serious violations, including cases of pressure on voters," she said.
Hovannisian met Thursday with Sargsyan. He said he'd discuss his talks with Sargsyan during weekend rallies.