— A group supporting Newt Gingrich will launch a nationwide radio advertising campaign Thursday morning intended to capitalize on questions being raised among conservative voters about rival presidential contender Mitt Romney.

The group, a super PAC called Winning Our Future, will launch a “major” ad campaign in all 50 states on popular conservative radio programs hosted by Rush Limbaugh, Glenn Beck, Sean Hannity and Mark Levin, said Rick Tyler, a spokesman for the group. The goal is not only to influence voters in upcoming primary contests but to raise money and foment concerns that Romney is not conservative enough to serve as Republican standard-bearer against President Obama in the fall, Tyler said.

View Photo Gallery: The former House speaker is seeking the Republican presidential nomination.

“There’s a revolt going on, and we need to position Newt at the center of that revolt,” Tyler said. “We’re going to be organizing a national effort capitalizing on what we perceive as a Republican Party revolt. People just can’t believe that we could possibly be nominating a Massachusetts moderate. The parade is already out there; we're just trying to jump in front of it.”

The ads, some of them 30 seconds long and some of them a full minute, pit the “establishment minority” of the Republican Party against the “conservative majority,” and paint Gingrich, with his history leading the Republican revolution of 1994, as the candidate who can effect true change in Washington. They seek to take advantage of a moment when the inevitability of Romney’s march toward the Republican nomination is in question, largely because of concerns within the GOP base about his conservative credentials. The ads also portray Gingrich as the natural alternative to Romney.

“We want to balance budgets and put the American people back in charge of the world's greatest economy,” the narrator of one of the ads says. “Only one man has done this before: Newt Gingrich.”

The ads direct listeners to a new Web site, www.timetochoose.com, that lays out the choice that Gingrich supporters say Republican voters are facing — between Romney, the moderate, and Gingrich, the true conservative. The Web site also encourages viewers to donate money.

“Speaker Gingrich and Senator Santorum both spent their careers in Washington — they went to do good and stayed to do well,” said Romney campaign spokeswoman Andrea Saul in an e-mailed response. “Mitt Romney, on the other hand, is a conservative businessman who spent 25 years in the real-world economy and wants to shake up Washington rather than defending business as usual on Capitol Hill.”

The ads come at a difficult moment for Gingrich, who is struggling to regain momentum after a series of losses in early primary and caucus states. Now, the Republican nomination is seen widely as a two-man contest between Romney and Rick Santorum, the former Pennsylvania senator. But Gingrich backers say Santorum's momentum, born from his triple set of victories last week in Colorado, Minnesota and Missouri, will fade quickly, while Gingrich, the former House speaker, will stay in the race until the Republican National Convention in August.

Winning Our Future is an independent super PAC that has received most of its money — about $11 million — from billionaire casino owner Sheldon Adelson or his relatives. The committee spent nearly all of that money in Iowa, South Carolina and Florida, but political circles continue to buzz about whether Adelson will give the committee more money in advance of critical upcoming contests in Arizona, Michigan, and the 10 states set to compete on Super Tuesday, March 6.

Tyler wouldn't say exactly how big the radio buy is; nor would he say whether more money is forthcoming from Adelson.

This post has been updated since it was first published.