DES MOINES, Iowa (AP) - Inviting contrasts with thrice-married religious convert Newt Gingrich, Mitt Romney cast himself as a man of consistency in religion and matrimony Wednesday as he and other GOP candidates went after the latest front-runner in a strikingly aggressive new phase of the Republican campaign.

"I'm a man of steadiness and constancy. I don't think you're going to find somebody who has more of those attributes than I do," the former Massachusetts governor said in a new TV ad that included grainy home videos of his wife and five sons. There was no mention of equivocations and policy reversals that his critics have pointed out.

Also on Wednesday, in hopes of reviving a flagging rival campaign, Texas Gov. Rick Perry launched an ambitious effort to compete against Gingrich for the support of Christian evangelicals by emphasizing his Christianity in a flood of new commercials in the leadoff caucus state of Iowa. Separately, Texas Rep. Ron Paul pressed his contention that former House Speaker Gingrich was simply a Washington insider who would eventually flame out.

"He's the flavor of the week," Paul said dismissively on CNN. "Our growth is steady."

The sharper tone marked a pronounced shift in the Republican presidential race away from policy differences and toward character distinctions, with the new GOP leader in state and national polls - Gingrich - clearly the focus a month before the Jan. 3 Iowa caucuses. The former Georgia lawmaker is getting a second look from Republican voters across the country after his campaign imploded earlier this summer, and time is running short for his opponents to slow him before the voting starts.