The U.S. Chamber of Commerce will air new ads in five states hitting Democratic Senate candidates and incumbents, on the heels of four TV ads released last week.

Targeting votes on health care, energy and regulations, the Chamber will go after Sen. Bill Nelson of Florida, Sen. Jon Tester of Montana, Rep. Martin Heinrich of New Mexico, Sen. Sherrod Brown of Ohio and Rep. Tammy Baldwin of Wisconsin. In Montana, for example, a narrator says, "For Jon Tester, there's no hiding from the truth. He sided with Washington time and time again. Take the health care law. The people didn't want it, yet Senator Tester cast a deciding vote, forcing it on Montana …"

See Florida ad here, the Montana ad here, the New Mexico ad here, the Ohio ad here and the Wisconsin ad here.

The Chamber aired ads last week in New Mexico, Hawaii, Nevada, and North Dakota.

The Chamber does not disclose its spending on particular ads, but in 2012 the group has promised its largest election-year investment to date. The Chamber bought $220,000 worth of air time last week in New Mexico, according to filings with the Federal Election Commission.

The five Democrats the Chamber will target this week, and the three campaigning in the additional states the Chamber targeted last week, are engaged in tight races that could tip the balance of power in the U.S. Senate in November.

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