The war in Israel. Abortion rights. Immigration policy.

National issues have dominated a special House election to replace George Santos in New York, as Republicans and Democrats take voters’ temperatures on issues that could tip November’s general election.

The race pits Tom Suozzi, a former Democratic congressman who represented the Queens and Long Island swing district for three terms, against Mazi Pilip, an Ethiopian-born local legislator. The open seat was created after the House voted to expel Mr. Santos, a Republican facing federal criminal charges.

The Feb. 13 contest carries unusual weight: A Democratic victory would narrow Republicans’ barely governable House majority to just two votes.

Here’s what you need to know about the race.

After decades in office, Mr. Suozzi is one of the most recognizable and well-liked figures on Long Island, but his party is deeply unpopular.

Ms. Pilip has a powerful local Republican machine behind her, but voters know very little about her.

Those inverse challenges are shaping the way both candidates are campaigning.

Mr. Suozzi has spent precious time and advertising money trying to separate himself from the Democratic brand. He has opposed his party’s position on local criminal laws and taxes, called for hardening border security and his television ads (which are running on Fox News) never mention his party affiliation — a gamble in a race where he needs base Democrats to turn out.