This recent poll indicating there is widespread support for public financing of elections caused me to dust off an idea that's been floating in my brain for a decade. I'm not just talking about Presidential elections, but Congressional elections as well. The main legal problem with any public financing scheme is how to make it mandatory and and still avoid Constitutional challenges by those who want to contribute to candidates.
One possible answer is to establish an inflation adjusted spending amount for each type of election, President, Senate and Representative (possibly adjusted for Senators by the state's population) and appropriate funds to each party's candidate for that office. Primaries will also have to be addressed. Any person can make a campaign contribution to the candidate of their choosing but those contributions must be remitted to the Treasury to offset the funds appropriated for that candidate. If the contributions exceed the amount appropriated the candidate can spend the surplus amounts.
Under this type of plan people and organization are free to contribute to candidates but they will not know if their contributions will ever be received by the candidate. If the public funding limit is set high enough it is likely that few campaigns will ever see "surplus" contributions.
I'd appreciate any thoughts people have.