By Tim Reid and Richard Cowan PHOENIX (Reuters) -Democrats on Saturday were one seat away from controlling the U.S. Senate next year, as vote-counting continued in deeply divided Nevada continued following Tuesday’s midterm elections and campaigning kicked off for a Dec. 6 runoff in Georgia. If incumbent Democratic Senator Catherine Cortez Masto manages to fend off Republican Adam Laxalt in Nevada, her party would then control 50 of the Senate’s 100 seats. A Democratic victory in Georgia next month would then give the party outright majority control of a 51-49 Senate. A Democratic loss in Geor…