RhodesCook.com

The Republicans are off to a good start in the 2010 election cycle, having handily won the first round – the trio of state elections that began with the gubernatorial contests in New Jersey and Virginia last November and concluded with the Massachusetts special Senate election a fortnight ago.

Round two – the upcoming primary season that begins tomorrow in Illinois -should provide us with valuable clues as to whether the Democrats will have company in their misery. In short, is the trend this year more anti-incumbent in nature than anti-Democratic in particular?

The primaries will be stretched out across the calendar until September, but are normally a low hurdle for incumbents of all stripes. No sitting senator or governor has lost a bid for renomination since 2006. Democrat Joe Lieberman of Connecticut was upended in his party’s Senate primary that year, while Republican Frank Murkowski of Alaska was beaten in the GOP gubernatorial primary by Sarah Palin.

At the House level, incumbent primary defeats are usually few and far between in all but the post-redistricting years that end with a “2.” That is when the lines are newly redrawn following the decennial census and incumbents find themselves with terrain that they have not represented before. In 1992, 19 House members were beaten in primaries. In 2002, there were eight.

But after that, House members tend to settle in for the rest of the decade, at least in terms of the primaries. In 2008, just four House members were denied renomination, and only two each in 2004 and 2006.

But in this year of voter angst, the primaries could be a more ominous danger zone for incumbents. The number of those defeated could go much higher than usual at both the congressional and gubernatorial levels. And if many of those casualties are on the GOP side, it would be a sign that not only Democrats should prepare for a difficult November election, so should Republicans.