Twitter reports today that the most retweeted message of the Republican National Convention was the tongue-in-cheek response of President Obama's campaign to actor Clint Eastwood's odd routine with an empty chair and an "invisible" Obama.

Eastwood carried on a rambling conversation with the empty chair Thursday during the convention's prime-time television hour. Obama's campaign responded by tweeting a photo taken from behind of Obama sitting in a leather chair, with a brass tag on the back identifying the chair as being reserved for "The President." The tweet said: "This seat's taken."

INTERACTIVE: USA TODAY/Twitter Election Meter

Twitter spokeswoman Rachael Horwitz said in an e-mail Sunday, "Wanted to share some news we broke this morning after doing some analysis over the weekend: @BarackObama's 'This seat's taken' Tweet was the most RTed of the Republican National Convention."

As of Sunday afternoon, the tweet had been retweeted 51,400 times.

Horwitz said it is Obama's second-most-retweeted message of all time, the top tweet being Obama's message in May announcing his revised position on gay marriage: "Same-sex couples should be able to get married." That message was retweeted 61,500 times.

By comparison, Twitter analysis site 140Elect.com reports Mitt Romney's top tweet of the convention was an end-of-the-week tweet: "Our economy runs on freedom, not government. It's time we put our faith back in the American people." It has so far been retweeted about 4,800 times.

On Saturday, in Ohio, Romney argued that if Obama was a football coach, his record on jobs would be 0-23 million, a reference to 23 million people who remain jobless. His campaign tweet, "When it comes to job creation, @BarackObama is 0-23 million. If your coach has that kind of record, you get a new coach" has been retweeted more than 3,100 times.

Zach Green, CEO of 140Elect, says Romney's most-retweeted message ever was his Aug. 11 announcement of Paul Ryan as his running mate. The tweet -- "I am proud to announce @PaulRyanVP as my VP. Stand with us today" -- has been retweeted 11,200 times.

Obama has a much larger following on Twitter than Romney, with about 19 million followers compared to Romney's 1 million. News reports indicate that more than half of Obama's followers may be fake accounts, but a recent study by Pew Research Center's Project for Excellence in Journalism found that Obama's followers are much more active on Twitter and he had many more retweets than Romney.