A thin margin separates Trump-endorsed Tito Asfura of the National Party and Salvador Nasralla of the Liberals in a partial preliminary vote count.
With final results pending, the leftist ruling party appears defeated, and two conservative candidates seem headed for a photo finish.
"President Trump had some very strong views on this election and he made them known," said the AS/COA vice president to the broadcast news outlet.
Amid growing polarization, all sides fear the November 30 vote will be contentious, an expert writes.
Fears of electoral fraud and voter concerns about jobs and insecurity loom over a three-way contest for the presidency.
Voters will choose their next president November 30 in a single-round vote. Polls indicate a three-way race.
Jobs, security and corruption are top of mind ahead of the November 30 election.