CLEAR LAKE, Iowa, July 4 — As thousands of people cheered along the Fourth of July parade route here, it was the tall man with the familiar white hair who made the crowd go truly gaga.

“Bob Barker! It’s Bob Barker!” two women shrieked upon seeing the former president, Bill Clinton, in the distance, as he and Senator Hillary Rodham Clinton of New York marched hand-in-hand.

When the women realized who it really was, they seemed just as thrilled, shouting, “Ohhhh!” and clapping madly. A game-show-host-turned-two-term-president: how can anyone, even Mrs. Clinton, compete?

No matter how much he tries to blend in, Mr. Clinton is one Oscar-worthy supporting actor who can sometimes upstage his leading lady simply by breathing. The Clintons’ political stagecraft — and their goal of shifting the spotlight to her — has been a work in progress since her presidential campaign began in January. This week, her husband’s first campaign jaunt on her behalf showed him in stages of adjustment — relaxed and jokey at times, a bit unpolished at others.