Rep. Tammy Baldwin's (D-Wis.) first U.S. Senate campaign ad goes after China for "cheating" in the labor market and highlights the congresswoman's work on sanctions against the country.

"In Wisconsin, we lead the entire nation in paper industry jobs. But China, they lead the world in cheating and it's costing us jobs in Wisconsin," Baldwin says in the ad. "So I brought Democrats and Republicans together to put sanctions on China now and punish them for making billions breaking trade rules."

The ad began airing Thursday across Wisconsin.

Wisconsin has "led the nation in papermaking for more than 50 years," and the industry employs nearly 53,000 workers in the state, the Baldwin campaign said in a press release.

"None of the Republican candidates for U.S. Senate have yet to speak out on China's unfair trade practices and take a stand to crack down on China's cheating," the release said.

Baldwin is running unopposed on the Democratic side for the open seat, which will be vacated by Democrat Herb Kohl when he retires after the election. Assembly Speaker Jeff Fitzgerald, businessman Eric Hovde, former congressman Mark Neumann and former governor Tommy Thompson are competing for the Republican nomination.

A Marquette Law School poll released on Wednesday found Thompson holding an eight-point lead over Baldwin in a hypothetical match-up. Baldwin was tied with Neumann and beating Fitzgerald and Hovde.