The results of last night Dem primary in PA could not have been more beneficial to John McCain. With Clinton winning by double digits, there is no way she will get out now which means it will go for at least another two weeks until the next major primaries in IN and NC.
The reason this is so helpful to McCain is that the longer they continue to have to fight each other, the less time they have to fight him. Also, the more divided the Dems become as they get behind their candidate the harder to win over for the eventual winner. Recent polling is showing that 1 in 7 Clinton supporters and 1 in 4 Obama supporters will either stay home or vote for McCain if their candidate doesn't win. That is very good news for the McCain camp.