Constitution Party candidates won at least four races, within the past 10 years. One of their candidates was elected to the Montana State House. Three of their candidates were elected to county offices, in Nevada.
While I lived in California, in 2000, I voted for the American Independent Party (the CA affiliate of the Constitution Party) candidate for the U.S. Senate. While I’ve been registered in Illinois, since 2002, I voted for four Constitution Party candidates (two for president, one for the U.S. Senate, and one for governor). In all five races, I thought that the republican nominees were too liberal and that the race wouldn’t be close. If I thought that the race would be close, I would have voted for the Republican, since I didn’t want to help split the anti-liberal vote, helping the Democrat win, with about 49% of the vote.
http://en.wikipedia.org/wiki/Rick_Jore
The situation with Rick Jore was key to whether the Democrats or Republicans would control the state legislature, so it got a lot of media attention at the time.
The Nevada affiliate of the Constitution Party was formed in 1967 and is known as the Independent American Party. They cite several people being elected to office, including a County Commissioner in Tonopah, the Mayor of Mesquite, and (in 2006) Jackie Berg as Eureka County Clerk/Treasurer and Cel Ocha as the Constable of Harry Reid's hometown of Searchlight.
The Nevada link is here: http://www.iapn.org/newiap/2010aboutus.html
Apparently Jackie Berg is still in office in a tiny central Nevada county, cited here: http://www.co.eureka.nv.us/clerk/clerk01.htm
She and Ocha are listed as current officeholders here: http://iapn.org/Office-holders.htm
Searchlight, other than being Sen. Harry Reid's hometown, is basically irrelevant. It's unincorporated and has only 539 people according to the 2010 census.
None of the other two Nevada people are still in office, or at least none of them are on the 2012 candidate list, posted here: http://www.iapn.org/newiap/2012candidates.html
As far as I can tell, this means the Constitution Party has managed to elect a grand total of five people to office in the last decade. Maybe there are others, but apparently only two of them are now in office.
Some may consider that a good track record of success. I don't, though I grant it may be a start.
I will give the Constitution Party serious consideration at the point that they start winning significant numbers of elections and prove they do more than split conservative votes leading to Democratic victories. So far, they aren't even posing a significant threat to the Republican Party, let alone the Democratic Party.
As conservatives, we need to focus on doing what we can to keep Romney from being nominated because I believe Romney is likely to lose to Obama, and even if he wins, he can't be trusted with key issues such as Supreme Court appointments. Whatever good the Constitution Party may be able to do long-term, they can't help defeat Barack Obama this year.