The United Transportation Union on Tuesday endorsed Sen. Hillary Rodham Clinton for the Democratic nomination for president, the first national union endorsement of the 2008 campaign.
"The UTU has a long history of picking winners early. Hillary will be a president that America's working families can count on. Time and again, as a United States senator, she has stood with us," UTU President Paul Thompson said in a statement.
Clinton is leading in national polls for the Democratic nomination. She said that she was honored to get the endorsement.
"America's workers have been invisible to this administration, and it's time they had an advocate in the White House," said the New York senator.
The UTU, which calls itself the largest railroad operating union in North America, represents 125,000 active and retired members in the railroad, bus and public transit industries.
The UTU also is one of the top political donors in organized labor, contributing $1.3 million in the 2004 federal elections, with 84 percent of the money going to Democratic candidates. The union gave $1.2 million in the 2006 elections, with 89 percent directed to the Democrats in a year in which the party reclaimed the House and Senate from the Republicans.
UTU was fourth on the Center for Responsive Politics' list of top transportation union contributors to political candidates.
All eight Democratic candidates have been courting the unions, participating in the AFL-CIO forum in Chicago earlier this month and touting their efforts to improve the lives of workers.
"Hillary Clinton's record has been friendly to working men and women of this country. She consistently has endorsed the necessity of a strong middle class," said the UTU's incoming president, Mike Futhey Jr. "The UTU will encourage its 125,000 active and retired members to support Hillary and other labor friendly candidates in 2008."
Several unions are expected to jump into the Democratic nomination fray as Labor Day approaches. The AFL-CIO, the nation's largest labor federation, has decided not to immediately endorse any of the Democratic candidates, freeing the federation's 55 member unions to endorse whoever they want.
For candidates, unions are critical for the money and the foot soldiers they can provide.
In the 2004 elections, organized labor gave $53.6 million to Democratic candidates and party committees, according to the Center for Responsive Politics. That amount increased to $66 million for the 2006 elections and is expected to increase again for 2008.