LANSING, Mich. (AP) — Democratic Rep. Elissa Slotkin is using her fundraising advantage in the race for Michigan’s coveted open U.S. Senate seat to drop $8 million on advertising in the final weeks leading up to the general election.

Slotkin is the overwhelming favorite to win the Democratic nomination in Michigan’s Aug. 6 primary and is expected to face a Republican nominee who will be heavily backed by national groups. Three Republicans are vying for the party’s nomination and former U.S. Rep. Mike Rogers has secured an endorsement from Donald Trump.

“This investment will be key to engaging and turning out voters in the final weeks of the campaign and sending Elissa Slotkin to the U.S. Senate,” Slotkin campaign spokesperson Austin Cook said in a statement.

While the ad reservation was planned before President Joe Biden’s troubling debate performance, Democrats nationwide are concerned about its potential impact on crucial down-ballot races, including Slotkin’s.

The TV ad reservations for October and November encompass the Detroit, Grand Rapids, Traverse City, and Flint media markets, spanning broadcast, cable, and digital platforms, according to a release shared first with The Associated Press.

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Democrats aim to retain the U.S. Senate seat held by Sen. Debbie Stabenow since 2001, following her retirement announcement last year. Michigan is among several battleground states that could determine which party controls the U.S. Senate for the next two years.

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Slotkin, serving her third term in Congress, announced her Senate campaign in February 2023. She has since garnered significant support through fundraising and endorsements, positioning herself as the frontrunner for the Democratic nomination. Actor Hill Harper is her only challenger but he faces a significant fundraising disadvantage.

Since announcing her candidacy, Slotkin has raised over $16 million and had $8.6 million in cash on hand as of the latest campaign finance update in early April.

The top three Republican candidates in the race have come nowhere close to Slotkin’s fundraising and Rogers had only raised $2.9 million through the end of March.

National Republican groups have become increasingly involved in the race as the seat appears more winnable for a party that hasn’t secured a Senate victory in Michigan since 1994.

In June, the Senate Republicans’ campaign arm announced $100 million in ad buys ahead of the 2024 elections in key swing states, including Michigan. National GOP groups have reserved over $14 million in total for ads following the Senate primary and leading up to the general election, according to the media tracking firm AdImpact.

Rogers has been endorsed by the National Republican Senatorial Committee, but the primary has become more contentious than the party anticipated. Businessman Sandy Pensler, another GOP candidate, has spent over $3 million on ads, with some attacking Rogers.

Democrats have made their own large ad buys in the Michigan Senate race as well. Senate Democrats’ campaign arm has reserved close to $10 million and their PAC has made an additional $17 million in ad reservations, according to AdImpact.