Republican Fred Thompson will begin airing TV ads in Iowa this week, casting himself as a consistent conservative and seeking to emerge as the top challenger to Mitt Romney who leads in state polls.

The ads, which will start airing Wednesday and will also be telecast nationally on FOX News Channel, are biographical spots designed to set the stage for the next eight weeks of campaigning. In them, Thompson appeals to the conservative sentiments that define many Iowa caucus goers.

"I grew up in a little hometown just like this," he says, speaking inside a small-town coffee shop. "Started the first Young Republican club in Lawrenceburg, Tennessee."

In one ad, lasting 60 seconds, he offers a broad view of his record and vision.

"In eight years in the United States Senate, I fought for tax cuts and for conservative judges," he says. "And I'm proud to have had a 100 percent pro-life voting record. Common sense conservative principles. Free people. Free markets and a government that doesn't tax and regulate us to death, but defends us and protects our borders."

Until now, the only ad Thompson has run was when he announced his candidacy in September. That ad ran during a Republican debate that he did not attend.

Thompson is scheduled to campaign next week in Iowa, a state where polls show him in a cluster with Rudy Giuliani and Mike Huckabee behind Romney.

So far in the presidential contest, the Iowa airwaves have belonged to Romney, who has spent more than $3.5 million in the state since the beginning of the year.

Thompson's ads are to run statewide at a high frequency, indicating a strong financial commitment to the state by Thompson.

They reflect a recognition within his campaign that Thompson still needs to define himself and his vision. Despite some negative campaign coverage over a slow start following his Sept. 5 announcement, Thompson has stayed competitive with Giuliani, Romney and John McCain in many surveys.

The spots play to Thompson's strength. A former senator and television actor, Thompson speaks directly and earnestly to the camera in a tone that would be familiar to fans of the NBC drama "Law & Order," in which he played a New York district attorney.

The longer ad also displays a photograph of a young Thompson greeting Ronald Reagan, a subtle reminder that Thompson has portrayed himself as a latter-day Reagan in the campaign. It also shows Thompson, who has been criticized for a languid style of campaigning, at his desk, sleeves rolled up and busy at work.

"My friends," he says, "we must remember that our rights come from God and not from government. And if we stick to our basic conservative principles, we will win next November and the United States of America will be better for it."