LITTLE ROCK — Election forecaster Nate Silver on Friday estimated Republican U.S. Rep. Tom Cotton’s chances of defeating Democratic U.S. Sen. Mark Pryor in Arkansas’ Senate race at 90 percent, a forecast that Pryor disputed.

LITTLE ROCK — Election forecaster Nate Silver on Friday estimated Republican U.S. Rep. Tom Cotton’s chances of defeating Democratic U.S. Sen. Mark Pryor in Arkansas’ Senate race at 90 percent, a forecast that Pryor disputed.


Also Friday, the Delta Grassroots Caucus slammed Cotton for declining to speak at its fall regional conference. A Cotton spokesman said he was too busy campaigning in the final days of the race.


Silver published his forecast on his website, FiveThirtyEight, in a piece that also predicted the chances of a Republican takeover of the Senate at 68.5 percent.


Silver noted that a University of Arkansas poll released Thursday showed Cotton with a lead of 13 percentage points over Pryor.


"No other poll of the state has shown Cotton with a double-digit lead, but he hasn’t trailed in a nonpartisan poll since Sept. 22," Silver wrote. "When the choice is between polls that show a candidate with a small lead and polls that show him with a large lead, he’s usually in good shape just a few days before Election Day."


Pryor said Friday, "What (Silver) does is, he takes the polling information and sort of synthesizes it and does an analysis on it. We’ve seen him be wrong in plenty of races over the last two or four years. I’m encouraged. I know we have a huge early vote number out there, and I think that’s great. When I get out around the state I hear people all over the state tell me they’ve already voted for me."


Cotton spokesman David Ray said Friday that Silver’s forecast, coming on the heels of the Arkansas Poll and other polls showing Cotton leading Pryor, is "encouraging."


"But we can’t let that get in the way of us continuing to work hard and get out every last vote that we can," he said.


In 2012, Silver correctly predicted the winners of all 50 states and the District of Columbia in the presidential race and correctly predicted the winners of 31 out of 33 Senate races.


Republicans need a net gain of six seats to win a majority in the Senate. Other states where Silver said the GOP has a high chance of picking up seats include Montana with a 98.8 percent chance; South Dakota, 99 percent; West Virginia, 98 percent; Louisiana, 77 percent; Colorado, 75 percent; Iowa, 67 percent; and Alaska, 67 percent.


Pryor spoke to reporters after giving a talk Friday morning at the annual meeting of Arkansas’ Independent Colleges and Universities in Little Rock. The association’s president, Rex Nelson, said Cotton had accepted an invitation to speak at the event but later cancelled.


Cotton’s Friday schedule included a morning appearance in Jonesboro with New Jersey Gov. Chris Christie, followed by appearances in Mountain View, Mountain Home and Fayetteville.


Pryor’s schedule for Friday afternoon included giving an in-person address to the Delta Grassroots Caucus at its fall regional conference in Helena-West Helena. He addressed the group via Skype on Thursday.


Caucus Director Lee Powell issued a statement Friday criticizing Cotton for declining an invitation to address the conference. Cotton told the group he could not participate because of scheduling conflicts; his campaign sent the group a letter on his positions that Powell said contained "generalized rhetoric with little substance."


"We all acknowledge and respect Congressman Cotton as a fine man with impressive credentials of service in the military and the law. But we urge him to get more involved in Delta regional issues and engage in a real dialogue rather than not even make a brief call-in to a major conference that includes five other major candidates from Arkansas and many other distinguished Arkansas leaders," Powell said in the statement.


Powell also noted that Cotton has voted for legislation that would have abolished the Delta Regional Authority and other regional commissions.


Ray said Friday that Cotton has spoken to the caucus three times in the past two years and held a meeting with caucus members at his office in Washington.


"It’s four days before the election. There’s a lot of places that we need to be, and we can’t be everywhere at once," Ray said.