ST. PETERSBURG — As Americans honored the memory of Dr. Martin Luther King Jr. on Monday, a Republican candidate for Florida House District 68 said President Barack Obama should be hanged for war crimes."I'm past impeachment," Joshua Black wrote on Twitter. "It's time to arrest and hang him high."The tweet caught the attention of Chris Latvala, a Republican candidate for House District 67."You aren't seriously calling for the killing of Obama are you?" Latvala replied. "I know you are crazy but good heavens. U R an embarrassment." Latvala added: "I make it my business when so called GOP candidates become an embarrassment to my beloved party."Black, 31, of Pinellas Park moved to Florida in 2007 after practicing street evangelism in St. Louis and works as a taxi driver. According to his campaign website, Black entered politics in 2012 when he tried influencing the presidential primary.The website says: "Republicans have a serious communication problem. Everything we say sounds like spears."Hours after the tweet, Black defended his comment. Obama should be held responsible for ordering a drone strike that killed a U.S. citizen overseas, he said."He should be executed for treason," Black said. "I think the appropriate punishment is death. They killed Benedict Arnold. (Obama) shouldn't be allowed to kill Americans without a trial." The political newcomer said he doesn't fear U.S. Secret Service agents showing up on his doorstep. Many voters might agree with his position, he said, adding: "I guess they're going to call me a racist now."After talking to a reporter, Black posted a lengthy message to supporters on Facebook."I make no apologies for saying that the President is not above the People. If ordinary Americans should be executed for treason, so should he."Pinellas GOP Chairman Michael Guju said Black doesn't know the secret details of the drone strike. "It is impossible to accept this statement," Guju said. "This is wholly unacceptable and unduly provocative."Black's opponent in the House race, Democratic state Rep. Dwight Dudley, said Black has the right to disagree with Obama's decisions. But he shouldn't call for Obama's hanging. "It's dangerous and unbecoming for someone who wants to lead to call for such violence and extremist action," he said. "Wow. I'm stunned."Times researcher Caryn Baird contributed to this report.