Some excerpts :
Over the last generation a cottage industry has built up decrying the lack of competition in congressional elections. Not only have the House reelection rates been high, but so have the margins of victory. In each election from 1998 through 2008, no more than 15% of House winners were elected with less than 55% of the total vote in their district.
But there are signs that the era of such pro-incumbent results may be ebbing. In 2010, the level of competition in congressional elections spiked. The number of sub-55% winners (often described as “marginals”) jumped to 25% of the entire House, the highest percentage in any election since 1992. And this quantitative measurement does not include such high-profile races as those involving Democratic Reps. Alan Grayson of Florida and Chet Edwards of Texas, where the incumbents lost in a landslide.
Rather than an aberration, the 2010 results could very well portend the start of a new, more competitive era of House elections—one that could last at least as long as the economy remains sluggish, voters remain disgruntled, and Congress appears dysfunctional.