Field locked in, but stage is still in flux, for Round 2 of Dem debates

Democratic presidential candidates, from left, former Colorado Gov. John Hickenlooper, entrepreneur Andrew Yang, South Bend, Ind., Mayor Pete Buttigieg, former Vice-President Joe Biden, Sen. Bernie Sanders, I-Vt., Sen. Kamala Harris, D-Calif., Sen. Kristen Gillibrand, D-N.Y., former Colorado Sen. Michael Bennet…