Republicans and Democrats in Columbus are launching a joint effort to explore hosting a national political convention. The Columbus 2016 coalition will lead the effort with the support of Mayor Michael Coleman, the Columbus Partnership and the city's convention and visitors' bureau. The groups say hosting a convention can mean as many as 45-thousand visitors and 150 to 200 million dollars for the city's economy. Ohio previously has hosted five national political conventions. Columbus has never been a host city.