A major Democratic super PAC is reserving nearly $80 million in fall TV ads across nine states with marquee Senate races as Democrats mount an uphill battle to take back the Senate majority.

The Senate Majority PAC (SMP) booked airtime in six of the 10 states that President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE won in 2016: Florida, Missouri, Indiana, West Virginia, North Dakota and Montana. The group also reserved ads in three of the Democrats’ best pickup opportunities: Nevada, Arizona and Tennessee.

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The ads will start airing after Labor Day and run through the November midterm elections. The SMP didn’t disclose how much will be spent in each state. The super PAC plans to make additional reservations in the coming months as well as reservations for digital ads.

“Democrats' chances in Senate races across the country continue improving because voters see that they are the candidates fighting for hardworking, middle class families," SMP President J.B. Poersch said in a statement.

“We are implementing an aggressive media strategy to combat the Republicans' baseless, partisan attacks and promote our candidates that are fighting for higher wages and lower health care premiums.”

Democrats are facing a tough Senate map — they need to defend incumbents in more than two dozen seats, while Republicans only need to protect eight seats.

But Republicans are looking to hang on to their slim one-seat majority in a cycle where they’re facing strong headwinds, since the president’s party typically loses seats in his first midterm election.

Senate Majority PAC has already poured millions into a handful of Senate battlegrounds where Democrats are playing defense. They’ve also spent heavily to protect Sen. Tammy Baldwin Tammy Suzanne BaldwinSenators introduce bipartisan bill to mandate digital apps disclose country of origin Keep teachers in the classroom Cher raised million for Biden campaign at LGBTQ-themed fundraiser MORE (D-Wis.), who's faced a barrage of negative ads from GOP outside groups. But Wisconsin was left off the list of initial ad reservations for the fall.

Democrats’ best offensive opportunity is in Nevada, where Democratic Rep. Jacky Rosen Jacklyn (Jacky) Sheryl RosenHillicon Valley: Election officials prepare for new Russian interference battle | 'Markeyverse' of online fans helps take down a Kennedy | GOP senators unveil bill to update tech liability protections Google, Apple, eBay to meet virtually with lawmakers for tech group's annual fly-in Senate Democrats demand answers on migrant child trafficking during pandemic MORE will square off against GOP Sen. Dean Heller Dean Arthur HellerOn The Trail: Democrats plan to hammer Trump on Social Security, Medicare Lobbying World Democrats spend big to put Senate in play MORE. Nevada has continued to trend towards Democrats, and Democratic presidential nominee Hillary Clinton Hillary Diane Rodham ClintonDemocratic groups using Bloomberg money to launch M in Spanish language ads in Florida The Hill's Campaign Report: Presidential polls tighten weeks out from Election Day More than 50 Latino faith leaders endorse Biden MORE won the state by more than 2 points in 2016.

The party also feels bullish about Arizona, where Democratic Rep. Kyrsten Sinema is expected to win the nomination and has been a prolific fundraiser.

Republicans have a heated three-way primary in the Arizona Senate race between establishment favorite Rep. Martha McSally Martha Elizabeth McSallyThe Hill's Campaign Report: Presidential polls tighten weeks out from Election Day Mark Kelly: Arizona Senate race winner should be sworn in 'promptly' New ABC/WaPost poll finds Trump edging Biden in Arizona, Florida MORE and two opponents running to the right of her: former state Sen. Kelli Ward and former Maricopa County Sheriff Joe Arpaio.

Democrats face longer odds in deep-red Tennessee, where the party hasn’t won a Senate seat in nearly 30 years. But the party feels good about former Gov. Phil Bredesen (D), who has led some early polls in a likely matchup against Rep. Marsha Blackburn Marsha BlackburnTaylor Swift on National Voter Registration Day: 'We need everyone' Democrats smell blood with new DHS whistleblower complaint Hillicon Valley: Election officials prepare for new Russian interference battle | 'Markeyverse' of online fans helps take down a Kennedy | GOP senators unveil bill to update tech liability protections MORE (R).