Weinstein has gained a reputation as both a top Democratic fundraiser and a shrewd Hollywood businessman, even turning down a movie proposal from Barack Obama.
According to The Hollywood Reporter, the movie producer made the comparison during a recent appearance on MSNBC's Rachel Maddow Show.
Discussing the growing disparity in fundraising for Romney's campaign as it surpasses President Barack Obama's, Weinstein compared the two politicians to films.
He said: "I'll give you an example of two movies that I distribute. I spent the exact same amount on both movies. One movie was called The King's Speech. It grossed $140 million, won a few Oscars including 'Best Picture', and did sensational based on its budget.
"The other picture was called Our Idiot Brother. And we spent the same exact amount of money on it and it grossed $25 million.
"Romney is Our Idiot Brother and Obama is The King's Speech. You can spend all the money in the world. If you've got a bad product, it doesnt matter."
Watch Harvey Weinstein's full interview with Rachel Maddow below: