Controversial liberal advocacy group MoveOn voted to endorse Barack Obama Friday, pledging to mobilize 1.7 million members in Super Tuesday states on behalf of the Illinois senator.

It was the first time the group's members ever voted to endorse a presidential candidate in a primary. MoveOn.org Political Action members hosted an Internet poll after John Edwards left the Democratic race Wednesday, and the majority of its surveyed members thought it was time to give an endorsement. The final vote favored Obama over Hillary Clinton by 70 to 30 percent.

Obama and MoveOn have both been vocal opponents of the Iraq war, and MoveOn.org executive director Eli Pariser said Obama is the best candidate to end the war, provide universal health care, address global warming and "change business as usual in Washington."

The vote further underscores the breadth of Obama's liberal support base, in the run-up to Super Tuesday, Feb. 5, when 22 states hold Democratic primaries and caucuses. Obama received the endorsement recently of Sen. Ted Kennedy and was ranked the most liberal senator of 2007 in National Journal Thursday.

Obama told reporters in a news conference Friday that even though Clinton describes how she would like to end the war, her explanation for her vote leading into the war is disingenuous. He said his opposition to the war from the start will make him the stronger rival to Republican front-runner and war backer John McCain in the general election.

Obama said in a statement Friday: "In just a few years, the members of MoveOn have once again demonstrated that real change comes not from the top-down, but from the bottom-up. From their principled opposition to the Iraq war -- a war I also opposed from the start -- to their strong support for a number of progressive causes, MoveOn shows what Americans can achieve when we come together in a grassroots movement for change. I thank them for their support and look forward to working with their members in the weeks and months ahead."

MoveOn claims 3.2 million members nationwide, and in its announcement pledged to connect thousands of its activists with Obama's volunteer operation, and make get-out-the-vote calls on Obama's behalf.

MoveOn launched in 1998 when it called on Congress to censure former President Bill Clinton and move beyond impeachment proceedings. The group stirred controversy recently when it ran a full-page ad in The New York Times in September that referred to Iraq commander Gen. David Petraeus as "General Betray Us."

Click here to read more about the MoveOn endorsement of Obama.

The Associated Press contributed to this report.