"Race is remarkably stable. 47% of country is MAGA or open to MAGA; 53% isn't. The goal of Harris-Walz is to coalesce as much of 53% as possible.
Today, Liz Cheney and Bernie Sanders are on the same side. That's not a bad coalition. The differences in polls are about the percentage of the 53% that Harris is getting. Trump stays stuck at 47%. If you were for Trump, you were for Trump months ago. You are looking for someone else to be acceptable. He's functioning as the incumbent.
Harris is winning a larger percentage of R's than Trump is of D's. She's winning independents. Could Trump win? Sure. But is there any element of the campaign that Trump campaign is performing at a higher level than Harris campaign? Think of it as a sports team match-up. She has better organization, more money, a better message and is performing at a much higher level than Trump. Most candidates are trying not to make mistakes at this stage of the presidential race. Exhaustion is a key factor. But Harris is improving. Maybe because she hasn't been a candidate for a year and a half.
In campaigns, the question you ask every night is would you rather be your campaign or the other guy? I'd rather be Harris."