Clint Eastwood has admitted he winged it at the Republican National Convention, deciding only at the last minute to ad lib a conversation with an empty chair, in remarks published Friday.

In his first public comment on the furor triggered by his eye-brow-raising routine, the Hollywood icon said he made it clear to Mitt Romney's aides that they could not dictate what he would do.

"They vet most of the people ... but I told them, 'You can't do that with me, because I don't know what I'm going to say'," he told his local paper, the Carmel Pine Cone, in an interview.

"I had three points I wanted to make: That not everybody in Hollywood is on the left, that Obama has broken a lot of the promises he made when he took office, and that the people should feel free to get rid of any politician who's not doing a good job.

"But I didn't make up my mind exactly what I was going to say until I said it," he said.

The 82-year-old actor-director sketched out his planned remarks after a quick nap at his hotel room, shortly before going to the Republican National Convention venue in Tampa, Florida, about 15-20 minutes before he was due on.

And the empty chair routine -- in which he chatted with an invisible President Barack Obama -- only occurred to him when he was backstage, shortly before he was due to go on.

"There was a stool there, and some fella kept asking me if I wanted to sit down," Eastwood said.

"When I saw the stool sitting there, it gave me the idea. I'll just put the stool out there and I'll talk to Mr. Obama and ask him why he didn't keep all of the promises he made to everybody."

He then asked a stagehand to put the stool on stage, near the podium. "The guy said, 'You mean you want it at the podium?' and I said, 'No, just put it right there next to it'."

Eastwood excused himself for talking for too long: he was only supposed to talk for five minutes, in a primetime spot shortly before Romney himself was due on stage, but ended up going on for more than double that.

"When you're out there, it's kind of hard to tell how much time is going by," he said, noting that the audience responded very positively. "They really seemed to be enjoying themselves."