(CNN) - Two Democratic sources tell CNN's Candy Crowley the International Brotherhood of Teamsters will endorse Barack Obama.
The Teamsters represents roughly 1.4 million members, making it one of the largest and influential labor unions.
Obama was endorsed Friday by the Service Employees International Union, the largest union with a membership of 1.5 million.
The Obama campaign also announced that the International Brotherhood of Boilermakers had decided to back the Illinois senator's White House bid.
UPDATE: Obama will meet with Teamsters leader James Hoffa later Wednesday.