Nate Silver: GOP favored to win Senate

[ProSense]

3. That's a really

There are 10 races that each party has at least a 25 percent chance of winning, according to our ratings. If Republicans were to win all of them, they would gain a net of 11 seats from Democrats, which would give them a 56-44 majority in the new Senate. If Democrats were to sweep, they would lose a net of just one seat and hold a 54-46 majority.

So our forecast might be thought of as a Republican gain of six seats — plus or minus five. The balance has shifted slightly toward the GOP. But it wouldn’t take much for it to revert to the Democrats, nor for this year to develop into a Republican rout along the lines of 2010.

...broad forecast.

Still, this is interesting:

Overall forecast

In consideration of these factors, we assess the probability of the Democratic or Republican candidate winning each seat. Where the choice of candidates is uncertain — for instance, in a race where a Democrat will face either a moderate, six-term incumbent U.S. representative or a poorly-financed tea party upstart, depending on the outcome of the Republican primary — the probabilities are meant to reflect a weighted combination of the plausible match-ups. Our assessment of the 36 races2 up for grabs this November is as follows: