NEW YORK — New York City Mayor Bill De Blasio was to become the first mayor in decades to sit out the city’s traditional St. Patrick’s Day parade over a dispute involving whether march participants can carry pro-gay signs. But Ireland’s Prime Minister refused to be sidelined, saying he’ll join the procession in Manhattan because the holiday is about Irishness, not sexuality.

New York’s Irish, their descendants and the Irish for a day will revel in the celebration of culture on Monday, but de Blasio’s decision to skip the parade underscores lingering political tensions over gay rights issues in the Northeast.

Boston’s Mayor Martin Walsh also opted out of his city’s parade on Sunday after talks broke down that would have allowed a gay group to march.

Parade organizers said they did not want the event to turn into a demonstration for a particular group, but Walsh said their plans prevented all Boston residents from participating fully.

Still, thousands of green-clad spectators came out to watch bagpipers and marchers in Boston, and organizers of a float intended to promote diversity threw Mardi Gras-type beads to onlookers. A similar scene played out in downtown Philadelphia.