This will give Dave Weigel heartburn:

In Massachusetts’ 5th Congressional District–a collection of mill towns and affluent and blue-collar suburbs north of Boston–the surprise issue was illegal immigration. Ogonowski made it the centerpiece of an anti-Washington campaign. An Ogonowski news release, for example, accused Tsongas of being “committed to giving cheap college to illegals at taxpayer expense.”

I had been guessing that Ogonowski’s anti-immigration positions were probably doing him more good than harm.  It shouldn’t be surprising that such an issue could work to Ogonowski’s advantage, especially in a special election with fairly low turnout.  That doesn’t mean that Ogonowski’s position wouldn’t help him in a regular general election, but it does remind us once again not to put too much stock in what MA-05 tells us about the strength of the two parties or the importance of particular issues.  What many people seem to be concluding from this race (GOP is reviving, Dems are in danger) is probably wrong, and no one should be investing the closeness of the outcome with much significance.