WASHINGTON — Democratic nominee Joe Biden’s presidential campaign will buy $280 million in advertising time in the fall, almost twice as much as the $151 million President Donald Trump has slated so far for the final three months before Election Day.

The Democrat’s campaign says the advance reservations of ad time will allow it to expand the battlefield to 15 states from the six it’s competed in so far.

The spending comes as the Trump campaign is rebooting its own ad strategy, redoubling its negative attacks on Biden, who is leading by more than 7 percentage points in national polls, according to the RealClearPolitics average. He’s also ahead in the six states most crucial to Trump’s 2016 victory: Arizona, North Carolina, Wisconsin, Pennsylvania, Florida and Michigan.

Biden has already spent millions in ads in those states. The campaign says it will expand that list to include four other states Trump won in 2016: Georgia, Iowa, Ohio and Texas.

The Biden ad strategy will also defend five states Hillary Clinton won four years ago: Minnesota, Nevada, New Hampshire, Colorado and Virginia.

Biden aides briefing reporters on their ad strategy Tuesday declined to assign specific numbers to each state. But they said the campaign would also rely on national ads _ particularly around major sporting and news events like each party’s nominating convention _ and ads specifically targeted to Blacks, Hispanics and Asian Americans.

The Democratic nominee will use that time to speak in his own voice about issues like the coronavirus pandemic, the economy and health care, said Biden chief strategist Mike Donilon.

“A key component of our message that differentiates us from the president is that we are speaking clearly and directly to the crisis at hand,” Donilon said. “It goes to the issue of leadership and a reassuring presence.”

Biden is trying to present the election as a referendum on Trump’s leadership on all those issues, while Trump has framed the election as a choice between his pre-COVID-19 economic record and the more liberal economic and social policies of the challenger.

Aides said Biden will make liberal use of 60-second ads. The longer format has slowly fallen out of favor in recent decades as attention spans have shortened and ads have become more negative.

So far, at least 36% of Biden’s ad spending has been on spots 60 seconds or longer. Trump has spent just more than 1% on longer ads, according to data from Advertising Analytics.

Biden’s ad buy includes $60 million in digital ads.

Campaigns take out early ad reservations to lock in time in key markets and demographics at more favorable rates, allowing them to spend more efficiently and potentially crowding out competing messages.

Trump has a head start. His campaign started buying fall ad time in late June, focusing on Arizona, Florida, North Carolina and Wisconsin.

As of Tuesday, Trump had $151.5 million in ads reserved, compared with $8.6 million for Biden, according to Advertising Analytics. And while Trump had ad slots reserved through Election Day, Biden had only purchased time through next Monday.