In Wisconsin, the campaign of Democratic Gov. Jim Doyle released a commercial Tuesday that features Fox, the Milwaukee Journal-Sentinel reported. Fox praises Doyle for supporting research and criticizes challenger Mark Green, who now claims to be a supporter as well, for a vote in Congress against a bill that would have expanded the number of stem cell lines that could be used in federally funded research.
In Missouri, Fox appeared in a commercial for Claire McCaskill, the Democratic candidate against Sen. Jim Talent, which aired during the first game of the World Series, the Chicago Tribune said.
In both commercials, Fox showed the physical signs of the disease he has lived with for 15 years.
Fox was also scheduled to appear Tuesday in Wheaton, Ill., at a rally for Tammy Duckworth, a Democratic congressional candidate.
Democrats hope stem cell research will be a wedge issue this year as gay marriage was for Republicans in 2004.
2014: The Year in Music [PHOTOS]