So at that point, Johnson had to take 62.5% of the remaining votes to come up to a tie. If your last figure of a Thune lead of 1,400 is with, say, 97% of the votes counted, then Johnson would need 61.7% of the remaining votes to tie Thune. He's not going to get that level of support from the remaining precincts.
More information, please, so we don't have to keep checking CNN.
Congressman Billybob