Barack Obama has clearly emerged in Gallup’s daily tracking poll as the favorite of Democrats over Hillary Clinton, but Clinton does slightly better than Obama in its May 19-23 survey when matched against John McCain. She leads McCain 49 percent to 45 percent with 3 percent undecided and 3 percent choosing neither, while Obama is in a statistical dead heat with McCain, with McCain ahead 46 percent to 45 percent with 4 percent undecided and 4 percent not stating a preference for wither. The margin of error is 2 percent. Clinton has pretty consistently had modest leads over McCain since early May, while Obama and McCain have traded the top position several times during the month.