DUNWOODY — Republican Karen Handel won a nationally watched congressional election Tuesday in Georgia, and she thanked President Donald Trump after she avoided an upset that would have rocked Washington ahead of the 2018 midterm elections. Returns showed Handel, a former Georgia secretary of state, winning about 52 percent of the vote over Democrat Jon Ossoff, who won nearly 48 percent in Georgia’s 6th Congressional District. “A special thanks to the president of the United States of America,” she said late Tuesday night as her supporters chanted, “Trump!