Story highlights The barrage is a late effort to keep their team afloat as support for Trump wanes

Democratic groups are increasingly focusing down-ballot

Washington (CNN) The Senate Leadership Fund is injecting $25 million into a half-dozen Senate battleground states, hoping to lift Republicans suffering under the weight of a historically unpopular presidential nominee.

The group -- part of the American Crossroads network founded by GOP operative Karl Rove and aligned with Senate Majority Leader Mitch McConnell -- said Tuesday it would blitz the airwaves to match Democratic hopefuls in Nevada, New Hampshire, North Carolina, Pennsylvania, Missouri and Indiana. The barrage is a late effort to keep their team afloat as support for Donald Trump wanes and Democrats appear to have the upper-hand in Senate battlegrounds.

The moves, first reported by Politico, were confirmed by Senate Leadership Fund spokesman Ian Prior.

The super PAC will invest $7.5 million in Nevada, where Rep. Joe Heck is fighting the GOP's only war to flip a Democratic seat; $5.2 million behind Sen. Pat Toomey in Pennsylvania; $4.1 million for Rep. Todd Young in Indiana; $3.2 million for Sen. Richard Burr in North Carolina; $2.6 million for Sen. Kelly Ayotte in New Hampshire; and $2.3 million for Roy Blunt in Missouri.

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