Monmouth has generally been a good poll for Warren; a lot of the differences from poll to poll seem to have to do with how well-informed and well-educated pollsters consider their likely voter universe to be. Still....
....it's at least becoming a real argument about whether Warren has caught Biden nationally. She hasn't in the poll averages and there's still a bit of cherry-picking going on. But we're talking about several polls that show her tied/ahead and no longer just 1 or 2 "outliers".
In most of these polls, Warren is gaining ground more than Biden is losing ground. (In a couple of them Biden is gaining also, though he's losing ground in others.) So the narrative of a Warren surge (sort of a slow-motion surge) is more robust than a Biden slump.
