(FORTUNE Magazine) - What do John Edwards and Arnold Schwarzenegger have in common? Movie star looks aside, both are joining a nationwide effort to raise state minimum wages.

In May, North Carolina and Pennsylvania will probably pass increases, joining recent hikers Maine, Arkansas, and Michigan. That will make 21 states with minimums above the federally mandated $5.15 set in 1997--over half raised since 2004. At least 15 other states are actively considering legislation, and pro-increase referendums will show up on November ballots in four states. Edwards and party chair Howard Dean are trying to brand the minimum wage as a Democratic issue. (It's a popular one: An April Pew Foundation poll found 83% support for an increase.) But Republicans like the Governator want to steal the Dems' thunder. Shrewd Republicans will likely agree to a modest increase now rather than face more generous, Democrat-rallying referendums in November.

Telis Demos contributed to this article.