Some are violently opposed to the idea. Washington led the Continental Army and basically founded the nation. Jefferson authored many of our founding documents. Lincoln preserved the union during the Civil War. What did Obama do that is equal to any of those accomplishments?
Others point out that, despite their accomplishments, all four of the presidents on Rushmore were white supremacists (yes, even Lincoln) and two were actual slaveowners. Obama bridged many racial divides to become president—that beats Teddy Roosevelt's achievements any day.
Everybody on Mount Rushmore is a racist piece of shit we should replace them with Obama, MLK, Harriet Tubman, and Kaep