When Robert Kennedy, Jr. pulled out of the national Democratic presidential primary, opting to run as an independent, it appeared that it might be clearing the way for President Joe Biden to run relatively unopposed in the primary.
Primary challenges, even ones where the incumbent wins, have served as omens for presidents who end up either withdrawing from the presidential race, or end up losing it, including Harry Truman, Lyndon Johnson, Gerald Ford, Jimmy Carter and George H.W. Bush.
Read the full story