The Republican Party and MoveOn.org sparred Wednesday over a new ad going after John McCain for saying he'd be willing to keep an American troop presence in Iraq for 100 years.

The ad, set to launch in Iowa and New Mexico Thursday to coincide with the 5th anniversary of Bush's now infamous "Mission Accomplished" speech, shows dozens of candles being lit on a cake bearing Bush's declaration, each representing another year in Iraq.

"100 years in Iraq -- and you thought no one could be worse than George Bush," the narrator says.

Republican National Committee spokesman Alex Conant said Barack Obama, whom MoveOn is supporting, should reject such mischaracterizations of McCain's statements.

"MoveOn.org is attempting to smear Senator McCain just like it smeared General Petraeus," he said, referring to the group's "General Betray Us" ad in The New York Times last year. "MoveOn.org is joining Barack Obama and the (Democratic National Committee) in maliciously misquoting John McCain ... Obama should prove his rhetoric is more than ‘just words' and stand up to MoveOn.org."

The MoveOn spot comes on the heels of a new DNC ad that also hit McCain's for his "100 years" comments.

McCain made the remark while campaigning in New Hampshire in January, and has since insisted that he has no intention of extending the war that long -- only that he would keep a U.S. military presence in the country as the military has does in Germany, Japan and other countries.

DNC Chairman Howard Dean has said that even if that's the case, McCain is "wrong" to want to keep a troop presence for a century.

MoveOn Director Eli Pariser fired back against the RNC Wednesday, saying, "Senator John McCain's position on Iraq has been clear -- he intends to keep our troops there for decades. This is not a one-time gaffe. It is the truth about John McCain's and George Bush's reckless foreign policy."

Click here to see the new MoveOn.org ad.

FOX News Mosheh Oinounou contributed to this report.