Former Vice President Joe Biden and his Democratic allies are preparing an advertising blitz that threatens to overwhelm President Trump in the closing weeks of the race for the White House, an onslaught of cash aimed at blowing up what Trump campaign officials once called their Death Star.

Biden’s campaign alone has reserved nearly a quarter billion dollars in advertising over the next five weeks in 18 swing states. Outside groups that support Biden have blocked off $112 million in their own airtime.

President Trump’s campaign, which spent heavily on advertising earlier in the year, is set to spend far less. So far, the campaign has reserved $130 million in airtime in 13 states, according to data provided by one Democrat and one Republican watching the advertising market.

Outside Republican groups have reserved $39 million in airtime.