Sen. Markey faces 2 challengers; now some pushing for a 3rd

Some Massachusetts voters see Sen. Edward Markey as potentially vulnerable to a primary challenge, and one group is even trying to persuade U.S. Rep. Joe Kennedy to run for his seat.Markey, a Democrat, has represented Massachusetts in Congress for decades — first in the House before winning John Kerry's former Senate seat in 2013 — but the state saw an incumbent lose just last year as Democrats elected more women and minorities.Ayanna Pressley defeated longtime incumbent U.S. Rep. Mi