He calls her “Mrs. C.” And she calls on him to add a little celebrity gloss to her presidential campaign.

Jon Bon Jovi and Hillary Rodham Clinton have been friends for more than a decade, uniting for state dinners at the White House and campaign fund-raisers in the Hamptons.

If it seems strange that a rocker who sings paeans of working-class New Jersey is so friendly with a senator and former first lady who chose a Celine Dion song for the theme ...