The Nevada Republican said in an appearance on CBS's "Face the Nation" program Democrats are likely to increase their majority in the Senate. He blamed, among other things, the souring U.S. economy for the Democrats' expected gains.
Republican Senate incumbents in Oregon, Minnesota, New Hampshire,and North Carolina each trail their Democratic challenges, polls indicate.
Democrats currently hold a 51-49 majority in the Senate. The number includes Democrats' support from independents Joe Lieberman of Connecticut and Bernard Sanders of Vermont. Lieberman, however, supports Republican Senator John McCain of Arizona over Democratic Sen. Barack Obama of Illinois for president.
"Democrats are poised to pick up some seats, the exact number we don't know," Ensign said. "That financial crisis really has been almost a body blow to Republicans."
Sen. Charles Schumer of New York, chairman of the Democratic Senatorial Campaign Committee, agreed his party would pick up more seats, but said it is unlikely Democrats would reach the 60-seat majority required to overcome Republican filibusters.
"Even though the wind is at our back, it's hard," Schumer said. "But I will say this, with 56, 57, 58, we'll be able to get a lot done in the Senate."