Wikisimpsons - The Simpsons Wiki
When the Simpson family had a blackout, Bart asked his mother if Barack Obama knew that DVDs needed electricity to work. Drederick Tatum has a tattoo of Barack Obama on his chest, and when he trained Marge to fight, he encouraged her to punch the tattoo.
When Superintendent Chalmers showed Bart a picture of all of the Presidents, Obama was one of the few that Bart recognized (identifying him as "black guy"). Lenny said that Carl thinks he has all the answers since Obama was elected.
At the 2012 presidential election he didn't vote for Obama as he already has one wife who tells him to eat healthy, plus Obama promised the death penalty but his father is still alive, so he chose Mitt Romney as he invented the Obamacare.
Homer tried to vote for Barack Obama in the 2008 Presidential election, but the voting machine was rigged to turn his vote into one for John McCain. After Homer made six attempts to vote for Obama, the machine sucked him in and killed him.