A super PAC allied with Senate Majority Leader Mitch McConnell will spend nearly $4 million in ads this fall against Indiana Democrat Evan Bayh to try to prevent him from winning back his former seat in the Senate.

The Senate Leadership Fund, dedicated to helping Republicans maintain their Senate majority, made the ad reservation on Friday, according to The Indianapolis Star.

The fund placed $960,000 in weekly ads for three weeks in September and one week in October, according to the report. It has already spent $1 million on the race so far, and $800,000 helping Republican Rep. Todd Young win his primary.

[Democratic Poll: Bayh (Still) Up Big]

A Monmouth University poll from earlier this month gave Bayh a 7-point lead over Young in the race to replace retiring Republican Sen. Dan Coats. An internal Democratic poll released last week showed Bayh leading by 18 points. 

The Rothenberg & Gonzales Political Report/Roll Call rates the race Tilts Democrat.