Democrats are pushing back against political prognosticator Nate Silver, who predicted on Sunday that Republicans have about a 60 percent chance of recapturing control of the Senate this November.

In a memo, Democratic Senatorial Campaign Committee Executive Director Guy Cecil mentioned past times that Silver has been wrong and said Silver's forecast is based on a limited supply of public polling.

"Nate Silver and the staff at FiveThirtyEight are doing groundbreaking work, but, as they have noted, they have to base their forecasts on a scarce supply of public polls," Cecil wrote.

"In some cases more than half of these polls come from GOP polling outfits. This was one reason why FiveThirtyEight forecasts in North Dakota and Montana were so far off in 2012. In fact, in August of 2012 Silver forecasted a 61% likelihood that Republicans would pick up enough seats to claim the majority. Three months later Democrats went on to win 55 seats."

In his latest Senate forecast — his first since starting up the FiveThirtyEight site at ESPN.com — Silver said Republicans are slight favorites to retake control of the Senate. In his previous forecast last summer, Silver described Senate control as a toss-up.

Republicans need to swing six seats in this year's elections to recapture Senate control. They're on track to win in West Virginia, South Dakota, Montana, and Arkansas, according to Silver. Four states remain toss-ups — Louisiana, North Carolina, Alaska, and Michigan. Based on that outlook, the most likely path to victory for Republicans involves swinging the four seats in which they're favored and winning two of the four toss-up races. Polls have continued to show a large Republican advantage in states with open Senate seats.

Silver also identified three Democratic-leaning seats — in Colorado, New Hampshire, and Iowa — that he said the GOP could plausibly win. Silver said Republicans could swing as many as 11 Senate seats. However, he said the GOP also facing significant challenges of their own in Georgia and Kentucky.

Other election forecasts have found similar results, including the Cook Political Report and the Rothenberg Political Report. However, Silver's name recognition has proven valuable for Democrats after he predicted President Barack Obama's victory in the past two elections. At least 11 times over the past four months, the DSCC has sent emails about the midterm elections with Silver's name in the subject line.

Though he dismissed Silver's projections, Cecil acknowledged that Democrats have an uphill battle ahead of them.

"We don't minimize the challenges ahead," Cecil wrote in the memo. "Rather, we view the latest projection as a reminder that we have a challenging map and important work still to do in order to preserve our majority."



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