Nicole Shanahan, Robert F. Kennedy Jr.’s running mate, said in a new interview that the Kennedy-Shanahan campaign faces a choice between either staying in the presidential race — which would “risk” helping Democratic Vice President Kamala Harris win — or dropping out to “join forces” with former President Donald Trump.

It’s a blunt admission after months of criticism from Democrats that the Kennedy campaign appeared more concerned with helping Trump than it was in running a truly…