The 82-year-old filmmaker knows all about sticking to the script, however refused to do so last night for Mitt Romney while discrediting Obama for his efforts as President of the United States, in a bizarre, unscripted endorsement for the Republican.

Standing on the convention stage with an empty chair, Eastwood carried on a sometimes rambling conversation with an imaginary President Barack Obama. The Oscar-winning director of "Unforgiven" and "Million Dollar Baby" criticized Obama for failing to turn the economy around and for wanting to close the Guantanamo Bay prison for terror suspects.

"How do you handle the promises you've made? What do you say?" Eastwood asked the imaginary Obama. "I know even some of the people in your party were disappointed you didn't close Gitmo," the Guantanamo prison.

"What do you mean 'shut up'?" said Eastwood, acting indignant. "I thought it was just because somebody had a stupid idea of trying terrorists in New York City."

The actor and director talked about Oprah Winfrey, the wars in Iraq and Afghanistan and lawyers. Eastwood said Obama has failed to deliver on his promises and it's time for Romney and his running mate, Paul Ryan, to take over.

"When somebody doesn't do the job, you gotta let 'em go," Eastwood said. The tough-guy actor of "Dirty Harry" fame drew a finger across his throat.

Twitter went crazy after Eastwood's speech, making him a trending topic.

Howard Kurtz, host of CNN's "Reliable Sources," tweeted that "Clint's empty chair act" was the "weirdest convention moment I have ever seen." Joe Scarborough, the conservative host of MSNBC's "Morning Joe," declared "a great night for Mitt Romney just got sidetracked by Clint Eastwood. Wow. That was bad."

Minutes after Eastwood began his speech, someone created the (at)InvisibleObama account on Twitter. It already has 17,000 followers and counting.

Comedian Roseanne Barr put it simply: "clint eastwood is CRAY" - a slang reference to being crazy.

Eastwood endorsed Romney earlier this month at a campaign event in Sun Valley, Idaho.