In the last several election cycles, three states have been the keys to winning the white house. With their combined total of 80 electoral votes, Pennsylvania, Florida, and Ohio are the most important to both parties.
In 2000, Florida decided the race.
In 2004, the winner had to take 2 of 3 to win, Bush carried Florida and Ohio, and won reelection.
In 2008, Obama took all three and cruised to victory.
All three have been toss up in the last 3 cycles.
In the midst of disappointment over some Senate races, please note the utter devastation visited upon the Democrats in these 3 states. The GOP won a Senate seat, Govenor, GOP assemblies, and every competitive house race in these states. It was a wipeout.
They are going to try and spin the NV and CA wins as critical, but I assure you that what they are really worrying about right now is what happened in these 3 states specifically.