There's something happening here since the first debate. 25 June, pre-debate, Biden was beating Trump by 10, Sanders by 10, Warren by 6, Harris by 4 and Buttigieg up by 4. 28 June its Biden over Trump by 8, Sanders by 6, Warren by 4, Harris by 4 and Buttigieg by 2. As of 7 July, it Biden over Trump by 10, Sanders leads Trump by 1, Warren is tied with Trump, Harris up by 2 and Buttigieg is tied with Trump.
RealClearPolitics - 2020 - Latest Polls
Way too early to read much into those polls. But I have to wonder if the debate showed the Democratic candidates way too far left for middle America. I don't mean geographically, I mean ideology, center, center right and center left. This is something I will keep an eye on.
Remember Trump won in 2016 because he carried the independent vote. The non-affiliated, those much less partisan to non-partisan, those who usually fall somewhere in-between the far right and far left of our two major parties.
The midterms, independents went for the Democratic congressional candidates 54-42 over the Republican congressional candidates. The Democrats picked up 40 seats. Now 35 of those 40 seats were won by moderate Democrats vs. 5 won by the far left democrats.
Who's the only moderate democrat in this presidential field that has been polled vs Trump? Biden of course. He's maintained his 10 point lead over Trump, all others have fallen. All others have come over looking very or possibly extreme left.
You can concentrate on turnout. Myself, I want a candidate that can attract the independent voter, Hillary couldn't. The Democratic Party is still the larger of the two major parties, that means Trump must win the independent vote or lose the election. Democrats just have to keep it fairly close. One other fact, the two major parties are shrinking. Independent rising, from 2006 when independents made up 30% of the electorate to today where independents make up 44%.
A word of advice for the Democrats, nominate a candidate attractive to independents, win by a landslide. Nominate another candidate independents dislike, a repeat of 2016 is very possible.