Mason-Dixon is out with new polling in Iowa, New Hampshire, South Carolina, and Nevada. In Iowa (Dec 3-6, 400 Dem LV, 400 GOP LV, MoE +/-5.0%), Clinton has a 2-point lead over Obama, and on the other side the Huckabee surge continues:

Democrats
Clinton 27
Obama 25
Edwards 21
Richardson 9
Biden 5
Undecided 11

Obama leads by 1.2% in the RCP Average for Iowa.

Republicans
Huckabee 32
Romney 20
Thompson 11
McCain 7
Giuliani 5
Undecided 19

Huckabee now leads by 6.2% in the RCP Average for Iowa.

In New Hampshire (Dec 3-6, 400 Dem LV, 400 GOP LV, MoE +/-5.0%), Clinton is clinging to just a 3-point lead over Obama, while Romney is up eight over Rudy on the Republican side:

Democrats
Clinton 30
Obama 27
Edwards 10
Richardson 7
Undecided 19

Clinton's lead in the RCP Average for New Hampshire has slipped to 8.0%.

Republicans
Romney 25
Giuliani 17
McCain 16
Huckabee 11
Thompson 6
Paul 5
Undecided 17

Romney is up 15.2% in the new RCP Average for New Hasmphire, but guess who's now in second place? John McCain.

In South Carolina (Dec 3-6, 400 Dem LV, 400 GOP LV, MoE +/-5.0%), Obama is within 3 points of Clinton, but one in four voters remain undecided, while on the Republicans side Huckabee has moved into first place:

Democrats
Clinton 28
Obama 25
Edwards 18
Biden 2
Undecided 24

Clinton leads by 6.5% in the RCP Average for South Carolina.

Republicans
Huckabee 20
Giuliani 17
Romney 15
Thompson 14
McCain 10
Paul 4
Undecided 18

Huckabee leads by 4.2% in the RCP Average for South Carolina.

Finally, in Nevada (Dec 3-5, 300 Dem LV, 300 GOP LV, MoE +/-6.0%)

Democrats
Clinton 34
Obama 26
Edwards 9
Richardson 7
Undecided 18

Clinton leads by 20.0% in the RCP Average in Nevada.

Republicans
Giuliani 25
Romney 20
Huckabee 17
Thompson 9
McCain 7
Paul 5
Undecided 14

Romney & Giuliani are tied in the latest RCP Average for Nevada.