Some 42 percent of voters surveyed by Daily Kos and SEIU believe pollsters were manipulating their sample sizes to benefit the incumbent president, while 40 percent do not. An additional 18 percent said they were not sure. That’s evidence that Republican claims that Democrats and minority voters are being oversampled in national polls could be resonating — and potentially undermining the momentum of the president’s early lead.

Some Republicans — most prominently among them strategist Dick Morris — began questioning the sampling of some polls last week when surveys showed President Obama opening up a sizable lead in swing states, including Ohio and Florida. Republicans have charged that the polls oversample minority voters, while polling firms say the sampling percentages reflect the electorate’s changing demographics.

But Republicans are particularly likely to believe that the polls are unfair, reporting by a 71-13 percent that polls are biased against their candidate. Members of the Tea Party suspect intentional skewing by a remarkable 84-5 percent margin.