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Statistician and political analyst Nate Silver said Sunday that Republicans have a roughly 75 percent chance of winning control of the Senate in Tuesday's election.

"It's still a close election," said Silver, founder of ESPN's FiveThirtyEight blog. "You have six or seven or eight races that could either way … [But] the polls are clear enough that the GOP will probably win the Senate."

Silver added later that "signs look fairly poor for Democrats" less than two days out.

The assessment echoed a consensus across the Sunday shows that Republicans will have a good night on Tuesday. The GOP needs to gain six seats to take a majority in the upper chamber.

Silver said Democrats "could carve out a path" to retaining control by winning in Alaska, Georgia and Kansas, but he said the party's candidates are "underdogs" in swing states like Colorado and Iowa.

"Democrats are certainly going to lose at least four seats," Silver said, citing Arkansas as one example.

The silver lining for Democrats might lie in potential run-off elections in December and January, he added.

"Democrats might have to bank on a run-off in Louisiana, a run-off in Georgia," he said.