President Joe Biden announced his reelection bid on Tuesday, despite his current approval rating being only 42.5%, according to FiveThirtyEight's average. While there is no correlation between approval ratings for presidents seeking reelection at this same point relative to the general election, approval ratings correlate strongly to actual vote margins by Election Day. The challenge for Biden is that approval ratings simply don't move as much as before. Since 2010, approval ratings have been sharply and consistently polarized on partisan lines, where a president's party views them positively and the opposing party views them negatively. Most undecided movement comes down to how independents feel. If the trend in correlation between approval ratings and final vote margins since Truman holds fast, a 42.5-percent approval rating for Biden on Election Day 2024 would be expected to result in a half-point loss in the popular vote.