The number of candidates for Congress who pledge to serve no more than a certain number of years in office is very high. The number of elected officials who uphold those pledges is very low. Hopefully there's a grad student out there researching the promise-keeping percentage.
Just look at Republicans challenging incumbent Democrats in Wisconsin (link to list of candidates and their sites). All three declared Senate candidates support restricting terms of office to 12 years. Although only one of them Leinenkugel explicitly promises not to stick around for more than 12 years himself, the implication is pretty clear.
And why not? Is there a better line of attack against an 18 year incumbent like Feingold?
Every single Republican congressional challenger (except Dan Mielke, who doesn't count) also supports term limits. Sean Duffy, whose incumbent opponent, 21-term Rep. Dave Obey, would be the ideal target of a term limits proposal, is one of the only Republicans who does not prominently display the issue on his website, although he has publicly expressed support for it in interviews and speeches. Red State, a conservative blog that hosted a live chat with Duffy, noted that 82% of Obey's district supported term limits.
Most of them have decided that 12 years is the right amount of time to do your thing in D.C. Dan Kapanke, the Republican challenging Rep. Ron Kind, has said he would only serve eight.
If any of these guys end up (surprise!) winning, it will be interesting to see how quickly the "term limits" tab disappears from their websites. If The Sconz still exists 12 years from now, make sure to remind me to hold them to account!
I'll have to look into the campaigns of Democratic challengers as well. There aren't too many meaningful ones in Wisconsin this cycle, since the three Republican incumbents are guaranteed re-election. But we'll take a look at state senate and assembly campaigns and see what the trend is.