Steelworkers' union backs Obama for White House

The United Steelworkers Union, a politically powerful U.S. labor group with 600,000 members, endorsed Barack Obama for president on Thursday as the Democratic Party began to rally around the Illinois senator.

The union endorsement came a day after former presidential candidate John Edwards announced his support for Obama. The steelworkers had endorsed Edwards last year.

Obama and his Democratic rival Hillary Clinton, a New York senator, competed hard for support from the steelworkers union after Edwards dropped out of the race in January.

"We find ourselves once again in agreement with Sen. Edwards, this time with his decision last evening to endorse Sen. Barack Obama," the union said in a statement, promising to work hard for Obama.

Obama has built a big lead over Clinton in the Democratic race for the right to face Republican John McCain in November's presidential election.

Clinton has resisted calls to get out of the race and promised to compete to the June 3 end of voting in the state-by-state nomination battles.