The endorsement by the 1.4 million-member union is another boost to the Illinois senator's campaign against his chief rival, Sen. Hillary Clinton of New York, who trails him in the race for the Democratic nomination.

"Senator Obama will stand with the Teamsters when it comes to fighting for working families," union President James P. Hoffa said in a statement.

Teamsters spokeswoman Leigh Strope said Hoffa, who was in Austin, Texas, was to meet with Obama, The Wall Street Journal reported.

Hoffa and the 29-member Teamsters executive board approved the endorsement, citing a belief Obama is best-suited to work on issues important to the union's membership, such as rebuilding the nation's infrastructure and problems related to ports and highways.