WASHINGTON - A major labor union and the liberal organization MoveOn.org are joining forces to air a provocative new ad portraying John McCain's Iraq policy as a prolonged presence that would involve a new generation of Americans.

Paid for by the American Federation of State, County and Municipal Employees and by MoveOn.org, the commercial represents an expansion by Democratic-leaning groups of a campaign against McCain. It also targets one of McCain's major assets - his public credibility on national security issues.

The ad will begin airing nationally Wednesday on CNN and MSNBC, and in Ohio, Michigan and Wisconsin markets. It will run for a week at a cost of $543,000. In the ad, an actress with an infant child speaks as if she were addressing McCain, the likely Republican presidential nominee.

"Hi John McCain," she says. "This is Alex. And he's my first. So far his talents include trying any new food and chasing after our dog. That, and making my heart pound every time I look at him. And so, John McCain, when you say you would stay in Iraq for 100 years, were you counting on Alex? Because if you were, you can't have him."

McCain has stressed that his goal is to reduce American casualties, shift security missions to Iraqis and, ultimately, have a non-combat U.S. troop presence in Iraq similar to that in South Korea. He has speculated that such a presence could last 100 years or more.

Last week, McCain aired his own commercial where he asserts, "I hate war." The ad is biographical, recalling his family's military service and his more than five years as a prisoner of war in Vietnam.

The campaign referred questions about the ad to the Republican National Committee, which said the country needs a president who listens to his commanders, not partisan groups like MoveOn.org. "Bringing peace and security to Iraq will require a commander in chief who won't allow partisanship to cloud his judgment," said spokesman Alex Conant.

Polls show that while a large majority of the public opposes the war, they split almost evenly between McCain and his likely Democratic opponent, Sen. Barack Obama, over who would better handle Iraq.

"The ad aims to give voice to so many people who are frustrated that we seem to be stuck in Iraq," said Eli Pariser, MoveOn.org's executive director. "It speaks to the worry that people have that we'll be sending another generation of young men and women to Iraq if we continue."

The AFSCME-MoveOn effort unites two forces that were on opposite camps during the Democratic primary. AFSCME backed Sen. Hillary Rodham Clinton, while MoveOn backed Obama, who clinched the nomination this month.

Paul Booth, executive assistant to AFSCME President Gerald W. McEntee, said the union has not yet endorsed Obama but said the ad illustrates "progressive forces coming together of the same mind about McCain."

MoveOn and AFSCME are paying for the ads through federally regulated political action committees.

Obama does not accept financial contributions from political action committees. He has called on outside nonprofit groups not to air ads in the presidential campaign. But his admonition has been aimed at groups that receive unlimited contributions, mostly from wealthy individuals. Political action committees, however, are restricted to receiving contributions of no more than $5,000.

WASHINGTON - A major labor union and the liberal organization MoveOn.org are joining forces to air a provocative new ad portraying John McCain's Iraq policy as a prolonged presence that would involve a new generation of Americans.

Paid for by the American Federation of State, County and Municipal Employees and by MoveOn.org, the commercial represents an expansion by Democratic-leaning groups of a campaign against McCain. It also targets one of McCain's major assets - his public credibility on national security issues.

The ad will begin airing nationally Wednesday on CNN and MSNBC, and in Ohio, Michigan and Wisconsin markets. It will run for a week at a cost of $543,000. In the ad, an actress with an infant child speaks as if she were addressing McCain, the likely Republican presidential nominee.

"Hi John McCain," she says. "This is Alex. And he's my first. So far his talents include trying any new food and chasing after our dog. That, and making my heart pound every time I look at him. And so, John McCain, when you say you would stay in Iraq for 100 years, were you counting on Alex? Because if you were, you can't have him."

McCain has stressed that his goal is to reduce American casualties, shift security missions to Iraqis and, ultimately, have a non-combat U.S. troop presence in Iraq similar to that in South Korea. He has speculated that such a presence could last 100 years or more.

Last week, McCain aired his own commercial where he asserts, "I hate war." The ad is biographical, recalling his family's military service and his more than five years as a prisoner of war in Vietnam.

The campaign referred questions about the ad to the Republican National Committee, which said the country needs a president who listens to his commanders, not partisan groups like MoveOn.org. "Bringing peace and security to Iraq will require a commander in chief who won't allow partisanship to cloud his judgment," said spokesman Alex Conant.

Polls show that while a large majority of the public opposes the war, they split almost evenly between McCain and his likely Democratic opponent, Sen. Barack Obama, over who would better handle Iraq.

"The ad aims to give voice to so many people who are frustrated that we seem to be stuck in Iraq," said Eli Pariser, MoveOn.org's executive director. "It speaks to the worry that people have that we'll be sending another generation of young men and women to Iraq if we continue."

The AFSCME-MoveOn effort unites two forces that were on opposite camps during the Democratic primary. AFSCME backed Sen. Hillary Rodham Clinton, while MoveOn backed Obama, who clinched the nomination this month.

Paul Booth, executive assistant to AFSCME President Gerald W. McEntee, said the union has not yet endorsed Obama but said the ad illustrates "progressive forces coming together of the same mind about McCain."

MoveOn and AFSCME are paying for the ads through federally regulated political action committees.

Obama does not accept financial contributions from political action committees. He has called on outside nonprofit groups not to air ads in the presidential campaign. But his admonition has been aimed at groups that receive unlimited contributions, mostly from wealthy individuals. Political action committees, however, are restricted to receiving contributions of no more than $5,000.