What can RFK Jr. do for Donald Trump?

Third-party candidate Robert F. Kennedy Jr. is expected to exit the presidential race and endorse Donald Trump at his rally in Arizona on Friday. Trump is also holding a rally in Phoenix today, and the choice of location is no accident: Arizona is famous for its independent voters, whom both Democrats and Republicans are desperate to win over ahead of an inevitably close election.

Potential quid pro quo. On Tuesday, Kennedy’s running mate, Nicole Shanahan, told an interviewer the campaign was weighing whether to “join forces” with Trump and suggested that Kennedy would do an “incredible job” as secretary of health and human services, a controversial choice given that Kennedy is a vocal supporter of the anti-vaccine movement. Trump later confirmed that he would probably “consider” appointing Kennedy to some role.

Election impact. Five percentof the voting population prefers Kennedy, and an August NPR/PBS/Marist poll found that that breaks down into 2% of Democrats, 3% of Republicans, and 12% of independents. Since voters who identify as Republican or Democrat would likely vote for their party’s preferred candidate in a two-way race, most of the votes up for grabs are independents.

“Trump will benefit marginally from Kennedy’s exit and endorsement,” says Eurasia Group’s US analyst Noah Daponte-Smith,as he will “likely gain one or two percentage points, but unlikely anything more. Many of Kennedy’s supporters either won’t vote or will vote for another third-party option.”