ANNAPOLIS, Maryland (AP) -- A national black Republican group is running a radio advertisement accusing Democrats of starting the Ku Klux Klan and saying the Rev. Martin Luther King Jr. was a Republican, a claim challenged by civil-rights researchers. Lt. Gov. Michael Steele, the black Republican nominee for Maryland's open Senate seat, disavowed the ad Thursday as "insulting to Marylanders." He said his campaign asked the Washington-based National Black Republican Association to stop running it. At an event in Baltimore, Steele said, "I don't know exactly what the intent of the ad was" but that "it's not helpful to the...