LANSING, Mich. – The conservative groups that supported Michigan’s new right-to-work law – winning a stunning victory over unions, even in the heart of American labor – vowed Wednesday to replicate that success elsewhere.

But the search for the next Michigan could be difficult.

National unions, caught flat-footed in the Wolverine State, pledged to offer fierce opposition wherever the idea crops up. They consider the laws a direct attack on their finances and political clout at a time when labor influence is already greatly diminished.

In addition, few Republican governors who could enact such legislation seem eager to bring the fight to their states.

“There is not much of a movement to do it,” Pennsylvania Gov. Tom Corbett told a Philadelphia radio station this week, according to the Associated Press.

His lack of enthusiasm was shared by two other governors who have battled with unions, Wisconsin’s Scott Walker and Ohio’s John Kasich.

Right-to-work measures like the one Michigan Gov. Rick Snyder, a Republican, signed Tuesday allow workers to opt out of paying union dues. Advocates say the laws, now in force in 24 states, offer employees greater freedom and make states more competitive in attracting jobs.

“If Michigan can do it, then I think everybody ought to think about it,” said Mark Mix, president of the National Right to Work Legal Defense Foundation.

He said he thinks at least one more state will adopt such a law before the end of 2013, and listed Alaska, Missouri, Montana and Pennsylvania among the top contenders.