WASHINGTON - Republican presidential candidate Newt Gingrich has opened his campaign wallet to buy his first television ads in Iowa, hoping to build on a surprise lead in the polls over Mitt Romney in the key Midwestern state that kicks off the 2012 nominating process early next month.

With businessman Herman Cain's withdrawal from the race, Gingrich, the former speaker of the House of Representatives, and former Massachusetts Gov. Romney look to be settling into a two-man contest to become the Republican challenger to President Barack Obama next year.

Gingrich's first TV ad of the campaign is a one minute piece entitled "The America We Love." It cuts between scenic rural images, people at work, Marines in dress uniform, a white church, a cowboy, the Statue of Liberty, the Iowa state capitol and the American flag. Gingrich speaks into the camera, ending with the message: "Yes, together we can and will rebuild the America we love."

The images harken to a small-town vision of American life, and nearly every person shown in the one-minute spot is white. A melody from the soundtrack to "Rudy," a popular 1993 movie about a short, working class boy from the Midwest who realizes his dream of playing college football, runs in the background.

The ad does not criticize Obama or any of Gingrich's Republican colleagues, but it does harken back to one of the most famous TV ads of all time: "It's morning again in America," a 1984 spot for then-President Ronald Reagan, which employed a similar montage of scenes from American life and patriotic symbols over a stirring soundtrack of woodwinds and strings.

The message is aimed at American voters who are experiencing the deepest economic downturn since the Great Depression more than 70 years ago, a lingering slump that leaves Obama vulnerable in the November election. Unemployment, while down slightly, is still at a relatively high 8.6 per cent, and millions of Americans having lost their homes to mortgage foreclosures. American voters tend to hold the president responsible for economic woes, and Obama's favourable rating is at the lowest of his presidency.

On Monday morning, Gingrich met with real estate baron Donald Trump at his office in New York City's Trump Tower. Trump had toyed with seeking the Republican nomination, focusing on the need to look into the issue of Obama's birth place. The president produced his birth certificate; Trump shut down his operation.

Gingrich has several events in New York on Monday as he tries to capitalize on his surging poll numbers. He arrived at Trump's office to a crush of media and curious onlookers. He said he was meeting Trump to talk about job creation.

Asked if his new strength in the Republican presidential contest was temporary or real, the former House speaker said it was "up to the American people to decide."

Trump will moderate a Republican debate on Dec. 27, and only Gingrich has accepted an invitation to the Des Moines, Iowa, gathering.

Texas Rep. Ron Paul and former Utah Gov. Jon Huntsman have declined the invitation. Trump on Monday said they were "joke candidates" and said he had not ruled out making his own run as an independent.

The Republican race has been so chaotic, however, that Obama is either leading or in a statistical tie in head-to-head matchups with the leading Republican contenders.

An Iowa victory would mark a stunning turnaround for Gingrich's once long-shot bid for the nomination. Most of his staff resigned in the summer as the former speaker of the House of Representatives was conducting a lacklustre, minimalist campaign that placed him near the bottom in the race.

Gingrich began rising, however, as Cain was brought low by allegations of sexual harassment and a 13-year extramarital affair. Cain denied any misconduct but ended his run Saturday, having slid from a brief period at the top of some polls into single-digit obscurity.

Now the other candidates are trying to attract Cain's conservative supporters. Gingrich's campaign was meeting with former Cain aides and advisers. With Cain's endorsement still available, Gingrich and his rivals were looking to schedule one-on-one meetings this week with him.

As the race narrows, Gingrich appears to have been the biggest beneficiary of Cain's slide. A Des Moines Register poll conducted Nov. 27-30 and released late Saturday found him leading in Iowa among likely Republican caucus-goers with 25 per cent support, ahead of the libertarian-leaning Paul at 18 per cent and former Massachusetts governor Romney at 16.

A separate NBC News/Marist poll showed Gingrich beating Romney, 26 per cent to 18 per cent, among likely Republican caucus attendees in Iowa.

While Gingrich has risen in Iowa, Romney still holds a sizable lead in surveys in New Hampshire, where he has a vacation home. The northeastern state holds the first primary election of the campaign season seven days after the Iowa caucuses. And the Obama campaign still appears to view Romney as the likely Republican nominee, given its continuing sharp attacks on what it says is his absence of a moral core politically.

Romney 's record of changing positions on critical issues to meet the wants of audiences has been a huge drag on his campaign. In the past, when he was campaigning or holding office in Democratic-leaning Massachusetts, he took moderate to liberal stances on issues like abortion and climate change and was responsible for a reform of the Massachusetts health care system that became the model for one that Obama pushed through Congress.

Republicans, especially the most conservative among them, have vowed to repeal the law because they view it as a government takeover of the administration of health care. Those voters express a deep distrust of Romney's conservative credentials, even though Gingrich also has changed many of his positions this year.