MADISON, Wis. — A conservative group that's part of the Koch brothers network says it is spending nearly $1 million more on a new television and digital ad attacking Democratic Sen. Tammy Baldwin.

Concerned Veterans for America announced the latest ad buy Wednesday. It comes after the group says it previously spent $2.8 million on ads against Baldwin.

The latest spot which the group says will air in several markets across the state accuses Baldwin of missing more than 70 percent of "important meetings" of the Senate Committee on Homeland Security and Governmental Affairs.

Baldwin spokesman Bill Neidhardt calls it a "tired attack" and cited figures showing that Baldwin had a 100 percent voting record on the committee.

Senators do not need to be physically present to have a vote recorded.