TAMPA — Clint Eastwood, the Hollywood filmmaker who knows all about sticking to the script, turned in what seemed like an oddly unscripted endorsement of Republican Mitt Romney.

Standing on the convention stage with an empty chair, Eastwood on Thursday night carried on a rambling conversation with an imaginary President Obama and pretended that Obama repeatedly told him to shut up.

Eastwood talked about Oprah Winfrey’s tears, Obama’s unfulfilled promise to close the US prison at Guantanamo, wars in Iraq and Afghanistan, and lawyers.

On a night when virtually every moment was scripted, Eastwood was among the only speakers not reading from a teleprompter as he spoke.

And it was a campaign gamble to allow Eastwood to speak just as the television networks tuned into the convention at 10 p.m., rather than substituting an evocative video of Romney’s life that played just before Eastwood’s bit.