SEIU backs Obama

The Service Employees International Union (SEIU) announced its endorsement Friday of Sen. Barack ObamaBarack Hussein ObamaObama attends UNC-Duke basketball game Obama, Steph Curry team up to tell young men of color: 'You matter' The Memo: Bernie Sanders’s WH launch sharpens ‘socialist’ question MORE’s (D-Ill.) presidential campaign.

The backing of one of the largest labor unions in America, with 1.8 million members, comes as Obama continues to build momentum in the Democratic presidential nominating contest.

SEIU President Andy Stern said the union's board voted overwhelmingly to support Obama.

"We now have one united SEIU, in terms of our way forward," Stern said. "We have an enormous amount of respect for Sen. Clinton, but it's now become clear members and leaders want to become part of an effort to elect Barack Obama the next president."

Obama received SEIU’s endorsement one day after winning the backing of the United Food and Commercial Workers union.