The Washington Post’s political prognosticators are promoting a model showing a 52-48 GOP majority with a 98 percent chance of Kay Hagan being reelected.
Political prognosticator Nate Silver, formerly of The New York Times, also predicts in his renowned Fivethirtyeight blog a 52-48 GOP majority but pegs Hagan’s reelection odds at 50-50. Alaska, North Carolina, Iowa, and Louisiana are pegged by Silver as the tightest races for US Senate seats currently held by Democrats.
Here’s some of Silver’s analysis:
If Americans elected an entirely new set of senators every two years — as they elect members of the House of Representatives — this November’s Senate contest would look like a stalemate. President Obama remains unpopular; his approval ratings have ticked down a point or two over the past few months. But the Republican Party remains a poor alternative in the eyes of many voters, which means it may not be able to exploit Obama’s unpopularity as much as it otherwise might.
Generic congressional ballot polls — probably the best indicator of the public’s overall mood toward the parties — suggest a relatively neutral partisan environment. Most of those polls show Democrats with a slight lead, but many of them are conducted among registered voters, meaning they can overstate Democrats’ standing as compared with polls of the people most likely to vote. Republicans usually have a turnout advantage, especially in midterm years, and their voters appear to be more enthusiastic about this November’s elections. Still, the gap is not as wide as it was in 2010.
The problem for Democrats is that this year’s Senate races aren’t being fought in neutral territory. Instead, the Class II senators on the ballot this year come from states that gave Obama an average of just 46 percent of the vote in 2012.1
Democrats hold the majority of Class II seats now, but that’s because they were last contested in 2008, one of the best Democratic years of the past half-century. That year, Democrats won the popular vote for the U.S. House by almost 11 percentage points. Imagine if 2008 had been a neutral partisan environment instead. We can approximate this by applying a uniform swing of 11 percentage points toward Republicans in each Senate race. In that case, Democrats would have lost the races in Alaska, Colorado, Louisiana, Minnesota, New Hampshire, North Carolina and Oregon — and Republicans would already hold a 52-48 majority in the Senate.
It therefore shouldn’t be surprising that we continue to see Republicans as slightly more likely than not to win a net of six seats this November and control of the Senate. A lot of it is simply reversion to the mean.2 This may not be a “wave” election as 2010 was, but Republicans don’t need a wave to take over the Senate. [….]