America First Action, a leading pro-Trump super PAC, will focus on Arizona, North Carolina, Pennsylvania and Wisconsin in a $23 million anti-Biden summer ad campaign beginning next week.

Why it matters: The ad buy signals which swing states the groups sees as most vulnerable for President Trump. Arizona and Wisconsin were not included earlier this year in the core battleground strategy.

• One PAC official tells Axios North Carolina and Arizona may be the tightest of these, then Pennsylvania, with Wisconsin seen as the most secure.

Between the lines: The ads, to begin July 24 and continue through Labor Day, will serve as a bridge before the Trump campaign's planned $100 million advertising blitzkrieg that will begin in September and run through the election.

By the numbers: The majority will be spent on broadcast (52%) and cable television (17%). Digital (14%) and mail resources (14%) also will be deployed.

State breakdown:

• Pennsylvania: $7.5m
• Wisconsin: $5.6m
• Arizona: $5.6m
• North Carolina: $4.5m

Details: America First Action's first round of ads focused on highlighting Biden's record on the North American Free Trade Agreement (NAFTA), painting him as soft on China and underscoring his desire to ban all fossil fuels. The group said the same themes may be incorporated in their future messaging, but they are watching closely which messages poll better in the specific states.