TAMPA, Fla. - In the battle for control of the United States Senate, the Democratic Party has little room for error and is particularly intent on protecting senators who are standing for re-election in presidential battleground states.
A pair of new polls by Quinnipiac University/New York Times/CBS News shows that Senators Bill Nelson of Florida and Sherrod Brown of Ohio have maintained strong leads over their Republican challengers.
In Florida, the poll found that Mr. Nelson was leading his Republican challenger, Representative Connie Mack, 53 percent to 39 percent. In Ohio, the poll found that Mr. Brown was leading his Republican opponent, State Treasurer Josh Mandel, 50 percent to 40 percent.
The Florida and Ohio polls of likely voters each have a margin of sampling error of plus or minus three percentage points for each candidate. The telephone poll was conducted by landlines and cellphones from Sept. 18 to 24.
While Republican groups initially targeted Ohio and Florida as potential opportunities to pick up seats from Democrats, with 41 days remaining until Election Day, Democrats hold clear advantages in both states.
A poll of likely Pennsylvania voters showed a somewhat closer Senate race, with Senator Bob Casey holding a six-point lead over his Republican opponent, Tom Smith, by 49 percent to 43 percent. That contest has not been widely seen as a pick-up opportunity for Republicans, party strategists say, but the poll found that the race has tightened since a July poll that found Mr. Casey with 55 percent to 37 percent for Mr. Smith.
