Actor Clint Eastwood and President Barack Obama are calling on the Supreme Court to strike down Proposition 8, California's gay marriage ban.

Eastwood,who created a buzz at the GOP convention by ridiculing an invisible Obama, was among the more than 100 Republicans who signed an amicus brief in support of a suit challenging the constitutionality of Proposition 8.

The Obama administration also filed a brief in support of plaintiffs. While the brief was written by the Department of Justice, it is widely believed that Obama made the decision on whether to weigh in on the case.

(Related: Gay groups cheer as Obama urges Supreme Court to strike down Prop 8.)

The Republican brief was organized by Ken Mehlman, a former RNC chairman who came out gay in 2010 to advocate on the issue, and includes many Republican heavyweights, including 4 former governors and top advisers to President George W. Bush.

The notion that Eastwood and Obama are on the same side of the issue has renewed talk in the media of a growing divide in the Republican Party and whether the issue of marriage equality, along with immigration reform, could deepen the split.