The National Association of Letter Carriers endorsed Sen. Hillary Rodham Clinton for president on Wednesday, saying the New York senator has the strength and experience to bring change to the White House.

"She's ready to lead this country from her first day in the White House," union president William H. Young said.

Clinton will officially accept the endorsement at an event at the union's headquarters later Wednesday.

"These hardworking men and women are part of the fabric of every community in America, and they deserve an advocate in the White House," Clinton said.

Young called Clinton the "runaway winner" when they surveyed their members on the presidential primary candidates.

"In the primary elections next year, you can count on letter carriers to deliver for Senator Clinton, and I am confident that in the years to come, President Hillary Clinton will deliver for every citizen throughout America," Young said.

The National Association of Letter Carriers represents 300,000 active and retired U.S. Postal Service city delivery carriers.

The union on Wednesday ratified a new five-year contract agreement with the U.S. Postal Service covering its 222,000 active mail carriers. The contract includes general wage increases of 8.85 percent over the term of the agreement, along with semiannual cost-of-living adjustments and new protections against the Postal Service contracting out letter carrier work to private firms and individuals.

The National Association of Letter Carriers gave $1.7 million in contributions to federal candidates and parties in 2006, with 89 percent to Democrats who took back control of the House and Senate, according to the Center for Responsive Politics. In 2004, the union gave $1.4 million to political candidates and parties, with 81 percent going to Democrats.

Rural letter carriers are represented by a different union.

This is Clinton's fourth union endorsement. She already has been endorsed by the United Transportation Union, the International Association of Machinists and Aerospace Workers and the Transportation Communication Union.