I noted that in a lot of polls, Hillary gets the worst % against Christie. In this poll, she is at 48% against Christie, but she is at 49%, 50% and 51% against the others.
The same in Alaska:
Hillary vs Palin: 46/40 (D +6%)
Hillary vs Huckabee: 39/47 (R +8%)
Hillary vs Bush: 38/47 (R +9%)
Hillary vs Christie: 34/45 (R +11%)
Hillary vs Rand Paul: 36/50 (R +14%)
and in Arkansas (excluding Huck)
Bush 46% Clinton 41%
Christie 42% Clinton 41%
Cruz 46% Clinton 42%
Huckabee 55% Clinton 39%
Paul 45% Clinton 42%
and in Kansas
Hillary - Jeb Bush: 39-45
Hillary - Huckabee: 41-46
Hillary - Rand Paul: 41-45
Hillary - Christie 38-42
Hillary - Ted Cruz: 42-43
and in North Carolina
Clinton 45% Huckabee 44%
Clinton 46% Bush 42%
Clinton 47% Paul 42%
Clinton 47% Cruz 41%
Clinton 45% Christie 38%
Why?
I wouldn't make much of a 1% difference at this stage.
Huckabee is an execrable match for the political culture outside the South except perhaps Alaska, which has many Texans and Oklahomans in the oil industry. Christie is a poor match for the political demographic who used to vote for Senator Jesse Helms. Jeb Bush is the definitive "establishment" Republican.