In the 2008 primaries, during which McCain and Obama opted out of the public financing system, the maximum amount a primary candidate could receive was about $21 million. Four years earlier, participating candidates received a total of $28.4 million, according to the FEC.
Given that in this election cycle the majority of candidates raising money for the primaries will be coming out of the GOP, which has consistently supported the elimination of publicly financed presidential campaigns, it's unclear how many will seek federal matching funds.
"For many of them, it's going to be a philosophical issue," Thomas said. "You can sort of see how being tied to taking any sort of government resources might be a political issue in the eyes of the Republicans these days.