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The fight for control of the Senate means more dollars are flowing to radio stations.

The Democratic Senatorial Campaign Committee has announced it will buy $79 million of advertising in nine states where key races are shaping up. The DSCC says it will spend on radio, television and digital advertising.

Montana will be especially radio-centric according to the group, as it supports incumbent Senator Jon Tester (D-MT) in his bid to hold onto the seat. The biggest portion of the money will go to television and to Michigan, where $11 million has been allocated to preserving the open seat. Another $10 million will be spent in Wisconsin as incumbent Senator Tammy Baldwin (D-WI) looks to hold onto her seat. Another $8 million will be spent in Pennsylvania where incumbent Senator Bob Casey (D-PA) is up for reelection. Other ad buys are planned for Nevada, Ohio, Arizona, Texas and Florida.

Some of the $79 million figure will go toward coordinated ad buys with the candidates, according to Politico. It also allows them to qualify for the lowest unit rates since they are working with the candidates. Christie Roberts, Executive Director of the DSCC, said that allows the group to communicate with voters in the most effective way as they focus their message on voter turnout.

Meantime, AdImpact reveals where the political races are likely to heat up in the coming months. It has released data showing where television ad reservations have been the largest in congressional races. The TV numbers give an indication of which markets radio stations could also see more activity as local stations typically receive more of the political dollars from congressional candidates than presidential contenders.

AdImpact says it has tracked $689 million worth of ads placed to run between July 1 and Election Day. The WinSenate PAC, which supports Democrats, has booked $222.6 million worth of ads, while the Republican-supporting Senate Leadership Fund has booked $77 million worth.

The review shows two Senate incumbents have also laid in large amounts of ad time. Nevada Senator Jacky Rosen (D-NV) has booked $13.9 million of ads in her state, while Tester has reserved ads worth $5.5 million. Both states are expected to be competitive, and the political spending reflects that. AdImpact says in Montana, there has been a combined $147.2 million in spending and future reservations so far. While in Nevada, the Senate election has already had $53.1 million in total spending.