The Quinnipiac University Poll was done between December 16th and 20th of a random national sample of 462 registered Democrats and 508 registered Republicans. The margin of error for Democrats is 4.6 points, and for Republicans is 4.4 points.
The Emerson College Poll was done between December 17th and 20th of a random national sample of 332 likely Democratic voters and 415 likely Republican voters. The margin of error for Democrats is 5.3 points, and for Republicans is 4.8 points.
The Rasmussen Poll was done on December 20th and 21st of a random national sample of 546 likely Democratic voters, and has a margin of error of 4.5 points.