Joe Biden is outspending President Trump this month with big TV ad buys in traditional swing states, as Trump focuses on digital ads to shore up his base in what should be Republican strongholds

By the numbers: Biden and affiliated Democrats have outspent Republicans by $4 million in Michigan, $3.5 million in Pennsylvania, $2 million in Arizona and $700,000 in Wisconsin, according to data provided to Axios by Advertising Analytics through July 28.

• Trump is widely outspending Biden, albeit on a smaller scale, on digital — most notably in Texas (which last voted for a Democratic president in 1976) and Georgia (where Trump won handily in 2016).

Why it matters: The president's allies once boasted of his prospects to expand the 2020 map into places like Minnesota, Nevada, New Hampshire and New Mexico.

• Trump's handling of the coronavirus and race relations has weakened him nationally, and polls arguably give Biden the rationale to stretch the map for his own party.

The big picture: At least right now, neither candidate is pursuing a particularly aggressive offensive strategy.

• Biden is playing it safe, focused on nailing down the places where Trump beat Hillary Clinton by a hair, rather than swinging for the fences.
• Meanwhile, Trump's spending suggests a defensive crouch that aims to hold the base and keep Biden voters home rather than win new converts.

Yes, but: Biden's play-it-safe strategy could change dramatically in the fall, but the campaign is holding its cards close to its chest.

• While Republicans have already booked $145 million in post-Labor Day TV ads in 11 states, the Biden campaign has yet to place its autumn buys — an approach that avoids telegraphing its strategy, but at some cost.

The bottom line: Biden is reinforcing a single public message in traditional battleground states — that Trump isn't fit to lead. Trump is broadcasting on different frequencies, with diffuse messages.

The messaging

An analysis of this month's spending shows Biden and allied Democratic groups are focusing on broad, anti-Trump TV attack ads in key battleground states.

• Most of Biden's messaging has focused on Trump's lack of leadership. He's offering a contrast and pledging to bring the country together.
• Meanwhile, the Trump campaign continues to play by its own rules, targeting vigilant supporters online with divisive topics like criminal justice reform, immigration and fake news.

What's next: A three-week snapshot before the nominating conventions may offer important clues on the campaign's geographical theories of the race, but it doesn't necessarily predict where the campaigns will fight it out after Labor Day.

• Trump appears to be using Facebook buys to do some management now, biding his time on big TV buys until he can see where the numbers are moving on the economy and COVID-19.
• Trump's strategy may change after independent expenditure campaigns spend the summer softening up Biden.
• Biden's current strategy is aimed at a win, not a landslide.