A Republican member of Congress plans to retire in May, opening up a seat in the House of Representatives. Rep. Steve Stivers (R-Ohio) announced Monday that he will step down on May 16 and become the president and CEO of the Ohio Chamber of Commerce. “For the past decade, it has been my honor and privilege to serve the people of Ohio’s 15th Congressional District. Throughout my career, I’ve worked to promote policies that drive our economy forward, get folks to work, and put our fiscal house in order,” Stivers said in a statement. “I’m excited to announce that I will be taking on a new opportunity that allows me to continue to do that.” Stivers, 56, has been in office since 2011. He won re-election last year with 63.4 percent of the vote. When Stivers departs Congress, Democrats will see their majority in the lower chamber grow from six …