WASHINGTON (CNN) -- The first presidential primaries may be a year away, but a liberal political action committee unveiled a 30-second ad Wednesday that attacks likely presidential candidate, Sen. John McCain, for supporting a plan to increase U.S. troops in Iraq.

MoveOn.org, a group that claims 3.2 million members, said it will purchase $250,000 in airtime in New Hampshire, Iowa, and on national cable denouncing the Arizona Republican senator on the ad that is scheduled to begin running immediately.

While scrolling through several images of McCain and President Bush embracing, an announcer says, "John McCain has done more than just embrace George Bush's failed policy in Iraq. It's actually his idea to escalate the war there. It's John McCain's idea to send tens of thousands more soldiers to Iraq. And to keep them there, with no timeline for bringing them home."

"The American people sent a message in November that they want a change that will bring our troops home," MoveOn.org Washington Director Tom Matzzie said in a statement. "Escalation is the wrong way -- sinking us deeper and deeper into the quagmire in Iraq."

But a spokesman for McCain, who is considering a bid for the presidency, dismissed the ad and charged that MoveOn.org does not represent mainstream America.

"MoveOn.org is an out-of-the-mainstream organization that has a long history of airing inflammatory material, even comparing the president to Hitler," Danny Diaz, a McCain spokesman told CNN. "It is not surprising that a liberal group opposed to military action after September 11th would attack Senator McCain for working to secure victory in Iraq."

The ad can be viewed on its website -- www.moveon.org.