I think what they were attempting by predicting victory was to turn oup the heat on the hold outs.
The meme is that “it was all set to pass, but then MrX, Y or Z blew it for everyone”.
If you are a politician, you may not to be Mr X, Y or Z.
And if the Dem congress is forced to become more moderate X, Y, and Z could very well turn out to be leaders.