Ok maybe the margin might be off but do people think 1 random voter switching from trump to Biden(who is already voting Bullock) means another non Biden voter will suddenly their vote from Daines to Bullock?
That is a good point, Biden winning a landslide reduces Bullock's relative overperformance (though it increases Bullock's actual margin probably) as the previously Trump-Bullock voters are most likely to vote for Biden, rather than Trump-Daines voters. I don't think Daines wins by 6 points though.
Yeah, "Daines will underperform Trump by xx points, so Biden coming within yy points of winning MT/doing yy points better than Clinton is good news for Bullock" is not a good way to approach this race. The national environment definitely helps Bullock (much like it helped Tester in 2018), but Biden gaining among voters who were mostly already supporting Bullock doesn’t.
I said this in another thread, but the range of possible outcomes for this race will remain stable irrespective of the national environment or fluctuations in MT/national polls: Bullock +5 - Daines +5 (really don’t see either candidate doing better than that, and even +4 is probably more likely at this point than +5 IMO).