Jonathan Lewis, entrepreneur and political activist and scion of the Cleveland-based Progressive Insurance Cos. fortune, is pledging to chip in $500,000 to defeat Proposition 8 if the entertainment industry does the same.

The proposition would restrict marriage in California to unions between a man and a woman.

His matching offer comes after Brad Pitt, and Steven Spielberg and Kate Capshaw, each chipped in $100,000 for the No on 8 campaign, after a flurry of stories showing that backers of Yes on 8 have outraised their counterparts. Curiously, at the time, little money to defeat the measure had come from the entertainment business, but the pace of fund-raising appears to be picking up. David Geffen recently donated another $50,000, adding to the $50,000 he already has given.

“With Election Day six weeks away, we are concerned that the entertainment industry hasn’t stepped up to the plate to fight this unnecessary initiative. We are pleased to see the leadership of Brad Pitt and Kate Capshaw and Steven Spielberg. Now it’s time for the entertainment industry as a whole to take the lead,” Lewis said in a statement.  “My family and I are issuing a $500,000 challenge to the entertainment industry. We will match the next half-million dollars that entertainment industry leaders contribute. This is an urgent time in the campaign, and we have to act now.”

Lewis said that the match also applies to contributions to fight Florida’s Proposition 2, an initiative similar to California’s Proposition 8.

Lewis’ father, Peter Lewis, is a longtime contributor to Democratic causes. Jonathan Lewis also has worked as an executive producer along with Russell Simmons, Kenny Edmonds and Tracey Edmonds on a R&B album to encourage young people to vote.