The Public Policy Polling survey was done on December 16th and 17th of a random national sample of 525 Democratic primary voters and 532 Republican primary voters, and has a margin of error for both parties of 4.3 points.
The Fox News Poll was done on December 16th and 17th of a random national sample of 390 Democrats and 402 Republicans. The margin of error for Democrats and Republicans is 4.5%-5.0%.