So Biden leads by 8 points in national polls and the polls are pretty much tied in key swing states. Big deal. At this time in 2016, HRC had a bigger lead nationally and was leading in swing state polls. On election day, she was rejected in those swing states by enough people to give Trump the WH. Presidential candidates usually get a bump in the polls after announcing their running mate. That didn't happen for Biden. Candidates usually get a bump in the polls after their party's convention. That didn't happen for Biden either.
A lot of political commentators like Chris Wallace believe the voters in this election will be about the virus. I don't buy it. I think the most important thing on the minds of voters is the economy. It's what I'm hearing from most people anyway. People are talking about Biden saying he wouldn't hesitate to shut the nation down if "scientists" say that would be necessary to stop the virus. Doing so would devastate the economy and drive unemployment levels higher than any level we have experienced in our lifetime. Another shutdown would destroy most small businesses. I seriously doubt right now many small business owners like Biden's plan and vote for him. The only thing that will help prevent the spread of the virus is a vaccine that works. Case in point; we have yet to stop the flu, but vaccines have prevented large percentages of people from getting it.
As the campaign progresses, we won't see Biden out on the campaign trail; he'll most likely remain in his basement protecting himself from the virus, while Trump travels the country meeting with the people. Many will begin to view Biden as a being afraid of the virus; not an admirable trait for someone who wants to be the leader of the free world. Harris will be the one out on the campaign trail and the more she talks, the more progressive the ticket will appear and turn moderates and independent voters off. They will see this as the ticket that is bad for the economy.