A conservative nonprofit that was the primary financial arm of a political network backed by the billionaire industrialist Koch brothers in 2012 is launching a second wave of TV ads targeting three Democratic Senate candidates, the group plans to announce Wednesday, bringing the amount of money the organization is spending on its new air effort to about $3 million.

New commercials from Freedom Partners Chamber of Commerce hit Sens. Mary Landrieu (D-La.), Mark Begich (D-Alaska) and Rep. Gary Peters (D-Mich.) for accepting campaign contributions from the insurance industry after pointing out that the lawmakers support the federal health-care law. The organization is spending nearly $2 million to air the ads over the next three weeks.

"Now we learn Peters took almost a hundred grand from health insurance special interests. The hypocrisy is shocking," says the narrator of the Michigan commercial.

The group announced its first two direct attack commercials -- technically "issue" ads -- on the same subject earlier this week. Those spots target Rep. Bruce Braley (D-Iowa) and Sen. Mark Udall (D-C0lo.) and are backed by more than $1 million total. Braley and Udall are running in competitive Senate races. So are Begich, Landrieu and Peters.

As The Post's Matea Gold pointed out Tuesday, engaging in a paid media effort  is new for the group. It has mainly been a vehicle for raising money and transferring it to a complex network of other groups.