Well, based on recent surveys, there is evidence that while Biden remains in the lead, his post-announcement polling surge has leveled off. Morning Consult’s latest tracking poll, for example, found Biden with 38 percent support nationally, down from a peak of 40 percent in early May. Quinnipiac University has also conducted Democratic primary polls multiple times since Biden entered the race, and it found Biden at 35 percent in a poll released on May 21, compared with 38 percent in a poll conducted right after his campaign announcement in April. If you compare his performance in national and state surveys taken in the three-week period that followed his campaign announcement — when he, like other candidates, experienced a surge in support — with the polls that were taken in the 10 days after that stretch, his average has dropped, to 35.0 percent from 36.6 percent.1
However, Biden is still well ahead of where he was before his campaign announcement. In the three weeks leading up to his kickoff, his polling average was 24 percent — 13 points lower than his average in the three weeks that followed his announcement. Biden’s post-announcement bump was especially large compared with the post-launch bounces of other candidates we can compare him with2 — as you can see in the table below, no other candidate saw an increase of more than 8 points.