They’re setting up here at the Park Plaza  for a celebration, but there is a palpable sense of anxiety here among staff and volunteers.  They know it’s close and are not exuding the  confidence that was evident on the eve of Scott Brown’s victory in 2010.  But like that special election this US Senate fight is a national race.  The eyes of the country are focused on Massachusetts to determine which party will control the US Senate.  Scott Brown has fought hard, and when he cast his vote in his home town of Wrentham he was amazed at the size of the crowd but he said the only thing left now is to wait for the results.