A qualitative study by the Democratic firm Greenberg Quinlan Rosner/Democracy Corps of 39 Nevadans who were undecided voters or weak supporters of either candidate found that more than one in four either moved from undecided toward supporting U.S. Sen. Barack Obama (D-Ill.) or from supporting U.S. Sen. John McCain (R-Ariz.) to undecided after viewing the Democratic presidential nominee's speech Thursday night.

"While this was clearly a qualitative exercise and not a representative survey, the movement we saw in attitudes toward the election and Barack Obama was dramatic," the authors wrote.

"On a thermometer scale of 0 to 100, Obama’s mean score rose 9 degrees (from 57 to 66 degrees) after voters saw his speech."