Rep. Vern Buchanan (R-Fla.) has made a huge $4 million airtime reservation for the fall campaign, according to a memo circulated by his campaign.

The reservation is a sign that Buchanan, a wealthy auto dealer, is willing to spend huge amounts of his own money to stay in Congress. His campaign had just shy of $1.5 million in the bank as of the end of March, a total that includes a nearly $500,000 contribution from the candidate.

Buchanan sits in a GOP-leaning seat based in the Tampa Bay area, but is facing an ongoing Ethics Committee investigation into whether he attempted to procure a false affidavit from a witness testifying about allegations of a straw-donor scheme. 

But it will be a costly venture for Democrats to try to knock him off — Tampa will be one of the most expensive media markets in the country this fall, because it covers a key swing area in a key swing state for the presidential campaign, a Senate race and a number of House races.

The Hill rates the race "lean Republican."