On June 21, the U.S. Senate overwhelmingly voted to add an amendment to the farm bill. The amendment would eliminate taxpayer funds to subsidize the expenses of holding political party national conventions (except that funding would still be provided for law enforcement and security), starting in 2016. See this story. It will be interesting to see if the U.S. House concurs. Thanks to Rick Hasen for the link.
The program for public money for national presidential nominating conventions has been in place starting in 1976. The only political party other than the Democratic and Republican Parties that ever received federal funding for its presidential convention was the Reform Party, in 2000.