Some of Mr. Trump’s Jewish allies sprang to his defense, arguing that the president was giving voice to a sense of befuddlement among many American Jews that too many Democrats appeared to be tolerating extreme views about Israel within their ranks. Matt Brooks, the executive director of the Republican Jewish Coalition, said the views of Ms. Omar and Ms. Tlaib, both of whom have made remarks condemned as anti-Semitic, were far outside the mainstream of their party and the country as a whole.

“There is a growing cancer within the Democratic Party right now of people who are supportive of B.D.S., who are advocating a shift in the U.S.-Israel relationship away from the strong bond that exists now between this administration and the government in Israel,” Mr. Brooks said. “As the center of gravity in the Democratic Party moves further and further to the left, this problem becomes clearer and more acute. It’s certainly not an indictment of the entire Democratic Party, but the unfortunate part is that none of them are speaking up and speaking out.”

In fact, the Democrat-led House voted overwhelmingly last month to condemn the boycott-Israel movement. During the debate, Ms. Tlaib, who is Palestinian-American, passionately defended the movement as a legitimate economic protest to advance human rights, calling Israel’s policies toward Palestinians “racist” and comparing the campaign to American boycotts of Nazi Germany.

On Monday in St. Paul, Ms. Omar raised the prospect of cutting off aid to Israel, arguing that a central purpose of the Israel visit that she and Ms. Tlaib had hoped to make was to conduct oversight over the $3 billion in funding that United States provides.

“We must be asking, as Israel’s ally, the Netanyahu government stop the expansion of settlements on Palestinian land and ensure full rights for Palestinians if we are to give them aid,” Ms. Omar said. “We know Donald Trump would love nothing more than to use this issue to pit Muslims and Jewish Americans against each other. The Muslim community and the Jewish community are being othered and made into the boogeyman by this administration.”

During the news conference, Ms. Tlaib broke down in tears when discussing why she turned down a last-minute offer by Mr. Netanyahu’s government to allow her to visit her 90-year-old grandmother in the West Bank if she promised not to speak out about the boycott during her stay.

“I’m her free bird, so why would I come back and be caged and bow down when my election rose her head up high, gave her dignity for the first time?” Ms. Tlaib said of her grandmother. “You don’t let anybody tell you that you’re less than or humiliate you.”