The presidential public campaign financing program (the Presidential Election Campaign Fund PECF]) is funded through "checkoff" designations on individual income tax returns. Choosing to participate (or not) in the checkoff does not affect one's tax liability or refund. Candidates who choose to participate in the program may receive taxpayer-funded matches of privately raised funds during primary campaigns, and grants during the general-election contest. Public funds also subsidize nominating conventions. The public financing system has remained largely unchanged since the 1970s. However, there is general agreement that, if the program is to be maintained, updates are necessary to provide greater financial resources and higher spending limits to participants. Some contend that the program should be curtailed or eliminated.