WASHINGTON (CNN) -- The National Organization for Women formally threw its backing behind Sen. Hillary Clinton's presidential bid Wednesday, an endorsement not entirely unexpected given that the New York Democrat is the only major female candidate running for the White House.

The organization gave its blessing to Clinton at the historic home of the National Women's Party in the nation's capital. Kim Gandy, NOW's president, said they will launch "Make History with Hillary," a new women's outreach movement that will help raise money and mobilize voters.

"When people tell me or tell any of you that a woman can't be elected president, I think we should say we'll never know unless we try, and we are trying, and we intend to succeed in this election," Clinton said.

Clinton was also endorsed Wednesday by tennis great Billie Jean King, and her campaign sent out a letter from former vice presidential candidate Geraldine Ferraro, who urged supporters to donate to Clinton’s campaign.