New York’s tumultuous primary season, which draws to a close on Tuesday, has no shortage of hard-fought, high-drama contests. But because of Mr. Maloney’s standing as the chair of the House Democratic campaign arm — and given the cast of prominent politicians who have gotten involved in the race — perhaps no New York primary is of greater national consequence than the battle for the newly redrawn 17th District, which includes parts of Westchester County and the Hudson Valley.

Mr. Maloney, backed by Speaker Nancy Pelosi and former President Bill Clinton, is fending off a primary challenge from State Senator Alessandra Biaggi, a left-leaning lawmaker who defeated a powerful incumbent in 2018, and now has the support of Representative Alexandria Ocasio-Cortez and a panoply of progressive organizations.

By every standard metric — fund-raising, television presence, available polling, endorsements and the assessments of several local elected officials — Mr. Maloney heads into Primary Day with a strong advantage. But New Yorkers are unaccustomed to voting in August, and low-turnout elections can be especially unpredictable.

On the ground, it is apparent that a contested race shaped by ideological, generational and stylistic tensions is underway. The winner is expected to face a competitive general election challenge from emboldened Republicans this fall.