After Hamas’s Oct. 7 attack on Israel, pro-Israel political groups put the Democratic Party’s most outspoken critics of the Jewish state on notice: An avalanche of spending was coming to either unseat them or force them to change their posture on the Middle East.

But the first expeted target of that avalanche, Representative Summer Lee of Pittsburgh, will face only nominal opposition in the Pennsylvania primary on Tuesday. And though groups like Democratic Majority for Israel and United Democracy Project, an affiliate of the American Israel Public Affairs Committee, have raised tens of millions of dollars to make good on their threats, they have so far mostly declined to spend it.

People involved in that pro-Israel effort say Democrats should not misinterpret the lack of an effort against Ms. Lee, a fierce critic of Israel whose western Pennsylvania district includes the Jewish neighborhood of Squirrel Hill, which remains traumatized five years after the biggest massacre of Jews in American history, at the Tree of Life Synagogue.

Pro-Israel groups were unable to recruit an experienced, well-known primary challenger to Ms. Lee. That is not the case in primaries to come, especially Representative Jamaal Bowman’s in New York in June and Representative Cori Bush’s in Missouri in August.

But there is another factor: Since the war in Gaza began, the politics surrounding Israel have shifted markedly, especially in Democratic primaries. Six months of punishing retaliation in Gaza have taken more than 31,000 Palestinian lives, according to the Gaza Health Ministry. Democratic leaders from President Biden on down are far more likely to encounter pro-Palestinian demonstrators than to encounter pro-Israel demonstrators.

On Saturday, 37 House Democrats voted against supplying military aid to Israel.