Will RFK, Jr. Matter in this Election?

How many third-party Presidential candidates can you name without using Google? Candidates outside the traditional two-party system have struggled throughout America's short history, with no third-party candidate ever making it close to winning a Presidential election (not to ignore Teddy Roosevelt, but his third-party run occurred after his Presidency against Taft and did end up failing). Oftentimes we discus these candidates as a liability - which of the two major candidates will suffer because of the small, but increasingly important, share of votes they pull away? While that framing is viewed as incorrect by independent candidates, in our two-party system the question is a legitimate one.

One of this year's third-party candidates, Robert F. Kennedy, Jr., was originally on the Democratic primary ballot but is now running as an independent, and announced his running mate this week. Is it right to say that President Biden has a reason to sweat Kennedy's pivot to a third-party candidacy? Or should former President be worried? The data shows this might not necessarily be true.