AUGUSTA — Sen. Arthur Mayo of Bath, newly re-elected to a second term, said Tuesday he had switched his party registration from Republican to Democrat. "It's a change in affiliation. It's not a change in philosophy," said Mayo, whose move across the political aisle boosts the Democratic Senate majority in the new Legislature to 19-16. Characterizing himself as a long-standing "liberal Republican," Mayo said "it has been increasingly difficult in the Senate Republican caucus" for someone with his political philosophy. Mayo said he believed the Republican Senate bloc has "moved to the right" and that at least some of his...