How Safe are Safe Liberal Seats ?

Fox News: Reports that even in birth place of JFK the great State of Massachusetts once liberal seats are under threat from the Republican wave facing the Democrats in November. If Democratic safe seats in the House go Republican this will make 1994 look like a major victory for Bill Clinton. If the Republicans can gain between 75 to 100 seats they can block any Obama policy, they will have the electoral mandate, they can push through a Bill to revoke ObamaCare, this will force POTUS to veto the Bill, the question that Democrats in the House and the Senate will have to ask is will they sustain a Presidential veto, when they run again can they afford to be seen as close to POTUS. The Oval will have to work hard to prevent a wipe out of Democrats on November.