PoliticsDemocratic Senator Bill Nelson of Florida will keep his job after fighting off a challenge from Republican Congressman Connie Mack, with the incumbent winning with strong support from age 50-plus voters. Floridians aged 50-64 — who comprised 28 percent of the vote — favored Nelson over Mack by 55-43 percent, according to exit polls. People 65 and older, 25 percent of the Sunshine State turnout, also went for Nelson, though by a narrower, 51-47 percent margin. The two Senate candidates …