Can you be bought? Here's how much each presidential candidate spent per vote

The presidential primaries don't cross many Americans' minds these days. It's convention season, and the public has turned its attention to the two nominees, strapping in for what promises to be an especially contentious general election.

But even as Donald Trump and Hillary Clinton prepare to duke it out between now and Nov. 8, most of the former presidential hopefuls remain financially mired in primary season.

The race for the White House isn't cheap. The most recent report from the Federal Election Commission shows that all of the former candidates are still paying off their presidential bids, even if they ended months ago. For instance, New Jersey Gov. Chris Christie's spent nearly $350,000 in June, though he dropped out of the race on Feb. 10.

The July FEC report covers campaign spending through June 30, the end of the primaries. Using this data and overall vote counts, Graphiq's politics site InsideGov ranked the candidates by financial efficiency, or how much they paid per vote. The spending totals used by InsideGov do not include money from super PACs. Though political action committees often back a specific candidate, they are technically separate entities from the campaign and cannot coordinate spending.

The candidates who paid the most per vote typically exited the race early, like Christie. These presidential contenders poured piles of money into early contests like Iowa and New Hampshire, but left the field soon after. Their vote totals took a dive after leaving the race, but some candidates still had a steady trickle of support. The people who stayed in the race the longest have the lowest cost per vote -- only one of the top five most efficient candidates dropped out before April.