1 Professional Prognosticators Senate predictions as of 29 April 2014. Current senate consists of 55 Democratic held seats 45 Republican held seats.
Charlie Cook 47 Democratic 46 Republican: Tossups (6 Democratic held seats) Alaska, Arkansas, Colorado, Louisiana, Michigan, and North Carolina. (2 Republican held seats) Georgia and Kentucky (Democrat to Republican West Virginia, Montana, South Dakota) (No Republican to Democratic seats)
For the Republicans to take control of the senate according to Cook, they must retain Georgia and Kentucky and win 3 of the 6 Democratic held seats he lists as tossups.
EP 51 Democratic 49 Republican: No toss ups (Democrat to Republican West Virginia, South Dakota, Montana, North Carolina) (No Republican to Democratic seats)
EP states the Democrats retain control of the senate.
Nate Silver 538, 49 Republican 48 Democratic: Tossups (3 Democratic held seats Alaska, Louisiana, and North Carolina. (Democrat to Republican Arkansas, Montana, South Dakota, West Virginia). (No Republican to Democratic seats.)
Nate says the Republican’s must win 2 of the three seats he lists as tossups. Nate and Cook are basically saying the same thing.
RCP 51 Democrat 49 Republican (Democrat to Republican, Alaska, Louisiana, Montana, South Dakota, West Virginia) (Republican to Democrat, Kentucky)
RCP no toss up predicts the Democrats remain in control of the senate.
Rothenberg 50 Democrat 49 Republican: Tossup (1 Democratic held seat) Louisiana (Democrat to Republican, West Virginia, South Dakota, Montana, Arkansas) (No Republican to Democrat seats)
For Stuart Rothenberg the Democrats are a lock to retain control of the senate. Even if Louisiana goes Republican, it would result in a 50-50 tie with Vice President Biden casting the deciding votes thus enabling the Democrats to retain their control.
Sabato 48 Democrat 49 Republican: 3 Tossups (3 Democratic Held seats) Alaska, North Carolina, Louisiana (Democratic to Republican, West Virginia, South Dakota, Montana, Arkansas) (No Republican to Democratic seats)
It comes down for the Republicans to win 2 of the 3 tossup seats if they are to gain control of the senate per Larry Sabato.