Democratic presidential candidate Bernie Sanders' positions on fracking, free tuition and breaking up big banks wouldn't sound out of place in an Oscar winning-actor's acceptance speech.

But in famously liberal Hollywood, long used as an ATM by Democratic campaigns, Sanders' message is not resonating as loudly as in other progressive bastions. The more moderate Hillary Clinton has far outpaced the Vermont senator in fundraising and has a deep line-up of A-list stars and top executives among her backers.

Celebrities don't sway votes, but they can persuade people to listen to a candidate's message, said historian Steven Ross, author of "Hollywood Left and Right: How Movie Stars Shaped American Politics."