First came Bill Foster's triumph in Illinois' 14th Congressional District. Then last weekend, Don Cazayoux was elected to the Louisiana congressional seat previously held by Republican Richard Baker. Democrats have been touting these victories in 2008 special elections as harbingers for a successful November. While special election wins don't always precede an electoral sweep, The Politico says these wins in Republican-leaning districts are exceedingly rare:

Since 1991, there have been 65 special elections. Only 10 — just over 15 percent — have changed party hands. Open seats in general elections are much more likely to change party hands. Since 1990, there have been 344 open-seat elections, and 34 percent have changed. Special elections often have low turnout, and voters usually favor the party that is dominant in the district.

The piece also shows that in recent years a congressional seat has only changed hands three times when the special election winner was from the minority party in the district. In 2008, we've already seen two, and after next week's run-off in Mississippi, a third could be on the way. In other words, it's a bad year to run as a Republican, a trend that should concern Illinois' GOP congressional delegation.