Teamsters Joint Council No. 62 sent a letter to Van Hollen last week noting the group is "determined to support your candidacy for U.S. Senate." The Van Hollen campaign made the letter public Tuesday.
Van Hollen, of Montgomery County, is running against Rep. Donna F. Edwards of Prince George's County for the Democratic nomination. Others, including Rep. Elijah E. Cummings, have expressed an interest in the race but few others have taken concrete steps toward launching a campaign.
Edwards and Van Hollen are running to replace retiring Sen. Barbara A. Mikulski.