Actor and director Clint Eastwood has been confirmed as a surprise guest Thursday night at the Republican National Convention.

Frazer Harrison / Getty Images Director/actor Clint Eastwood accepts the award for Distinguished Collaborator onstage during the 14th Annual Costume Designers Guild Awards With Presenting Sponsor Lacoste held at The Beverly Hilton hotel on February 21, 2012 in Beverly Hills, Calif.

Eastwood recently thrust his support behind GOP presidential candidate Mitt Romney, who will receive his official nomination at the convention tonight.

Earlier this year, a Chrysler ad narrated by Eastwood that aired during the Super Bowl appeared to endorse President Barack Obama, prompting the actor to respond that he was not backing either candidate. He then went on to voice his support for Romney earlier this month at a fundraiser in Idaho.

Eastwood will address the convention Thursday night in Tampa, Fla., before Romney accepts his nomination. Romney will be introduced by Florida Sen. Marco Rubio.

NBC's Kelly O'Donnell and Sue Kroll contributed to this story.