Teamsters president James Hoffa is expected to win another five-year term heading one of the nation's largest unions.
With most of the votes counted, election results show Hoffa garnering about 57 percent of the vote and challengers Fred Gegare and Sandy Pope splitting the rest.
The 1.3 million-member union represents mostly truck drivers and warehouse workers. Hoffa has held the office since 1999.
Hoffa was one of the first labor leaders to support President Barack Obama in the 2008 election. His union is expected to support the president's re-election campaign.
It remains the only union in the nation under federal supervision, the result of a racketeering lawsuit that was settled in 1989.