Given how divided your country is right now, it's very likely the vote will be close. I don't believe it will be a landslide either way. It's also true that a lot can happen between now and the actual election date, and that 4 months or thereabouts is a long time in politics.
While you could look at the polls and say that biden is likely to win based on that, as we saw in 2016, polls can be very wrong too. So I personally I would take the polls (whatever poll it is you want to talk about) with a grain of salt.
The bottom line is: while some here (on both sides of the political argument) are blinded by their political allegiances; I personally try to base my opinions on actual evidence. And given once again how divided your country is right now, there isn't enough evidence in either direction to be able to even take a meaningful guess as to who's going to win out of trump and biden. I can tell you that it will be the undecided voter that will determine who the next US president will be. And most of them likely won't make up their minds until much closer to the actual election taking place, if not on the day itself. It's also true that at least some Sanders supporters will likely vote for trump rather than biden, like they did in 2016. But again, right now it's impossible for anyone to even guess which way it's going to go, unless you own a crystal ball.
And even Republicans in tough seats still have to be careful not
to alienate trump supporters. Because you have to remember that the most loyal trump supporters don't really care about the party, they care about trump getting back in, and trump is a republican
"president" at the end of the day, not a democrat "president". And there's no way they are going to vote for a democrat that supports biden instead of trump. More importantly, the republicans need a majority in both houses to control both houses, which means smooth sailing for trump's bill's getting through.