The GOP presidential campaigns of Mitt Romney and John McCain -- rocked in different ways by a highly negative "push poll" targeting Romney's Mormon faith -- demanded Friday that the New Hampshire attorney general investigate who is behind the tactic.

The attorney general's office said it was investigating the phone calls.

As part of the poll, which began Sunday, callers have been asking voters in Iowa and New Hampshire whether they know that Romney is a Mormon, that his five sons did not serve in the military and that Mormons believe the Book of Mormon is superior to the Bible.

The callers also inquire whether voters are aware that Romney, the former Massachusetts governor, accepted deferments to avoid military service in Vietnam while he was on a mission with other young Mormons in France.

At the beginning of the 20-minute survey, voters are asked whether they are aware of McCain's decorated military service during Vietnam. That has led many voters to assume the poll was sponsored by the Arizona senator's campaign. But McCain's campaign immediately denounced the effort and insisted it had nothing to do with it.

"Whoever did this wanted to hurt us by implication," said Mark Salter, a senior aide to McCain. "That's why we were very forceful."

Romney's supporters have long feared that a shadowy whispering campaign would arise at some point targeting his Mormon faith. The new push poll may be the most explicit anti-Mormon message to emerge in the campaign so far.

But Dean Spiliotes, a New Hampshire political analyst and founder of NHpoliticalcapital.com, said the attack may inadvertently help Romney.

"It certainly gives Romney a platform to speak about his religion, something that people have advised him to do," Spiliotes said. "It may also get him some sympathy from voters who don't like seeing religion mixed so intimately with politics."

Push polling, in which negative information is disseminated under the guise of a poll, is a well-known tactic, if a widely condemned one.

Former Rep. Charles Douglas (R-N.H.), vice chairman of McCain's New Hampshire campaign, handed his complaint to Deputy New Hampshire Atty. Gen. Orville Brewster Fitch II on Friday, calling the phone calls "repugnant.

"We find the whole thing a very bad trend eight weeks before the primary," Douglas told Fitch.

Aides to Sen. Judd Gregg (R-N.H.) also filed a complaint with the state's attorney general on behalf of the Romney campaign. Campaign officials said they are providing names of people who received the calls.

"Whichever campaign is engaging in this type of awful religious bigotry as a line of political attack, it is repulsive and to put it bluntly un-American," said Romney communications director Matt Rhoades. "There is no excuse for these attacks. Gov. Romney is campaigning as an optimist who wants to lead the nation. These attacks are just the opposite. They are ugly and divisive."

Leaders of the Church of Jesus Christ of Latter-day Saints say the church embraces the truths accepted by other Christians but also accepts "additional information" from later revelations.

Romney blames McCain

Campaigning in Las Vegas, Romney called the poll "un-American." And he essentially blamed McCain, saying it was a direct result of the McCain-Feingold campaign finance legislation, which he said has been "ineffective" in removing special-interest money from campaigns.

Aides to McCain pointed out that before the legislation was passed, McCain was a victim of push polling in South Carolina during the 2000 presidential primary.

"It is appalling, but not surprising, that Mitt Romney would seek to take advantage of this disturbing incident to launch yet another hypocritical attack," said Jill Hazelbaker, McCain's spokeswoman. "It's the hallmark of his campaign."

New Hampshire law requires all political ads -- including phone calls -- to identify the candidate behind the effort, or at least the candidate who is being supported. The push polling calls were made by Utah-based Western Wats and did not identify a candidate that the calls were intended to help or hurt.

Previous news reports have linked calls by Western Wats to the Tarrance Group, which works for former New York Mayor Rudolph Giuliani. Ed Goeas, the head of the Tarrance Group, told The Associated Press that there is no connection between Giuliani and Western Wats.

Katie Levinson, Giuliani's communications director, said there is no room for push polls in the campaign.

"Our campaign does not support or engage in these types of tactics, and it is our hope other campaigns will adhere to the same policy," she said.

McCain says calls 'cowardly'

McCain, who arrived in New Hampshire Friday for a three-day swing through the northern and western parts of the state, called the phone calls "cowardly."

During the 2000 presidential race, South Carolina voters received calls and pamphlets alleging that McCain's wife, Cindy, was a drug addict, and that McCain had an illegitimate black daughter. The whispering campaign also suggested that McCain was mentally unbalanced after spending 5 1/2 years as a prisoner of war in Vietnam.

After the South Carolina primary, which McCain lost, McCain's campaign made thousands of "Catholic voter alert" calls in Michigan informing voters that then-Gov. George W. Bush had appeared at Bob Jones University and describing Jones, the institution's leader, as someone with a history of anti-Catholic statements.

The phone calls infuriated Bush, who said he did not like being called a bigot. McCain won Michigan by 6 percentage points but lost the Republican nomination.