The chart above is from the Gallup Poll. Gallup interviewed 19,405 adults in 2020, and the survey has a 1 point margin of error.
It shows the recent actions of the Republican Party (claims of a rigged election and widespread fraud, even though there is no evidence of it) is driving people away from that party. In November, there was only a 3 point difference between those claiming to be Republican (45%) and those claiming to be Democrats (48%).
But in December, that difference has grown to 11 points (50% Democrat and 39% Republican).
