Tribeca’s P.S. 234 was a popular political stop Wednesday on the first day of school. Left, Brooklyn Councilmember Bill De Blasio was looking for Downtown votes in the public advocate Democratic primary next Tuesday. He is endorsed by Borough President Scott Stringer, right, one of the few city officials who does not have a primary next week. At center is Margaret Chin, one of the candidates in the Lower Manhattan City Council primary. Two of Chin’s opponents, Pete Gleason and PJ Kim, also greeted parents outside the school.