Sanders is in the lead and Fake News spiked the last poll because it’s likely some of Warren’s support would have moved over to Sanders if it was clear he was the likely winner.
If Biden is really doing as badly as the spiked Des Moines Register poll shows, he will have a horribly low delegate count because of the 15% threshold per locality.
More info on the spiked Des Moine register poll here if anyone has not seen it:
https://www.powerlineblog.com/archives/2020/02/bernie-mania-update.php