LOUISVILLE, Ky. (AP) – A national Democratic group ignited Kentucky’s only open congressional race with claims the Republican candidate’s family business shipped work to Mexico that could have stayed in Kentucky.

The attack launched Tuesday by the Democratic Congressional Campaign Committee was denounced by Republican Brett Guthrie’s campaign, which called the ad a “blatant lie.”

Guthrie’s family’s company, Trace Die Cast Inc. in Bowling Green, said its products are Kentucky-made, and its attorney threatened to sue Louisville TV stations unless they pulled the spot.

The ad spiced up what had been a low-key race between Guthrie and Democrat David Boswell for the 2nd District seat held by Republican Rep. Ron Lewis, who is retiring. The district covering parts of central and western Kentucky has become a target for Democrats hoping to pad their majority status in the U.S. House.

Guthrie and Boswell, colleagues in the state Senate, have generally avoided attacking one another, but the DCCC ad signaled a new tone six weeks before the Nov. 4 election.

The DCCC has reserved more than $840,000 in TV time for the 2nd District race. Those ads would be a big boost for Boswell, who has lagged behind Guthrie in campaign fundraising. Guthrie started his TV advertising earlier this month, accusing the Democratic-led Congress of inaction while gas prices soared.

Boswell debuted his first TV ad Tuesday – a folksy spot in which the Democrat is seen driving his pickup truck and expressing his opposition to abortion and higher taxes and support for gun rights. Boswell also declares his opposition to “bad trade deals that send our jobs to Mexico and China.”

The Boswell ad was meant to burnish his conservative credentials in the mostly rural district.

Meanwhile, the DCCC ad targets the business started by Guthrie’s father. Brett Guthrie is an executive at Trace Die Cast, which makes aluminum die castings for automakers, employing several hundred workers.

The DCCC said the ad was based on a 2004 newspaper article in which a business professor said Trace Die Cast sent cast aluminum parts to Mexico for finishing that then returned to Bowling Green for assembly.

The DCCC said a search in the Kentucky region showed 15 companies could do the work that went to Mexico.

“There’s absolutely no grounds to pull the ad,” said DCCC spokeswoman Kyra Jennings.

But the Guthrie campaign and his family’s business said the accusations were flat-out wrong.

“No products manufactured by Trace Die Cast are outsourced to foreign companies,” attorney George Strickler said in writing the Louisville TV stations demanding that the commercial be taken off the air. “Any products shipped to foreign companies are sold to them by Trace Die Cast Inc.”

Those foreign companies purchasing products made by Trace Die Cast do not do work for Trace, and those products are not returned to Trace, he said.

Executives at two Louisville stations said they would review information from both sides before a decision is made on the ads. Until then, the commercials will keep running, they said.

Trade policy has emerged as a key issue in a district that lost considerable jobs, especially in the garment industry, to low-wage oversees operations since the North American Free Trade Agreement.

The DCCC ad accuses Guthrie of supporting “unfair” trade agreements and claims NAFTA has cost Kentucky in excess of 14,000 jobs. The NAFTA trade pact was adopted while Democrat Bill Clinton was in the White House.

At a televised debate Monday night, Boswell was critical of NAFTA, or the North American Free Trade Agreement struck last decade by the U.S. with Canada and Mexico.

“I believe that we need to come full circle back around and redo that,” he said.