(Pat Sullivan/AP, File) (Pat Sullivan/AP, File)

San Antonio Mayor Julian Castro, the keynote speaker at the 2008 Democratic National Convention, will attend next month's Steak Fry hosted by Sen. Tom Harkin (D-Iowa), according to a person with knowledge of the event.

The Steak Fry, now in its 36th year, is a regular stopover for potential presidential candidates trying to make inroads in the Hawkeye State. A relatively new senator named Barack Obama attended the Steak Fry in 2006, shortly before launching his 2008 presidential campaign.