WASHINGTON — The decision by Israel to bar two Muslim members of Congress from an official visit to the Jewish state is raising deep concerns in both parties that the hard-line views of President Trump and Prime Minister Benjamin Netanyahu are endangering the longstanding ties between the United States and Israel.
Mr. Trump has spent months attacking the two freshman Democrats, Representatives Rashida Tlaib of Michigan and Ilhan Omar of Minnesota, which has roiled the Democratic Party, and he has tried to paint Republicans as Israel’s only true friend in Washington. Mr. Netanyahu’s years of hard-line settlement policies and rigid bond with the ultra-Orthodox Jews have also alienated Democrats, including many American Jews.
But if Israel becomes a partisan issue in the United States, experts and advocates warn, it will be bad for both countries. Tensions deepened on Friday, when Ms. Tlaib rejected an offer by Israel to allow her to visit her grandmother on humanitarian grounds, but only if she agreed in writing not to “promote boycotts against Israel” during her trip.
“There is a perception, right or wrong, true or untrue, that the Netanyahu administration and the Trump administration are working hand in glove,” said Mark Mellman, president of Democratic Majority for Israel, a nonprofit that works to ensure the Democratic Party remains pro-Israel.
Israel’s stance, he said, has made his task harder: “In our hyperpartisan world, the friend of my enemy is my enemy, and to the extent that Democrats look at Trump as the enemy, if they see Israel and the Netanyahu administration as operating hand in glove, that gives them real pause.”
Mr. Netanyahu has long made clear his affinity for the Republican Party. His relations with former President Barack Obama were famously strained — so much so that 2015, in a rare breach of protocol, he circumvented the White House in accepting an invitation to address the Republican-led Congress. Representative Nancy Pelosi, then the Democratic leader, called the address an “insult” to the United States and dozens of Democrats skipped it.
With Mr. Trump in office, the Netanyahu-Republican alliance has strengthened, generating fears that bipartisan American support for Israel — a cornerstone of relations between the two countries since the founding of the Jewish state in 1948 — will erode.
Those fears are so real that even the American Israel Public Affairs Committee, the powerful and assiduously bipartisan pro-Israel lobbying group known as AIPAC, has split with the Netanyahu government on its decision. AIPAC typically backs Israel no matter who is in power, but its view is that while presidents and prime ministers come and go, support for Israel in Congress is essential.
“What is the one mantra of the pro-Israel organizations for 30, 40 years?” asked William Kristol, a conservative critic of Mr. Trump who fought Mr. Obama’s policies toward Israel. “It’s congressional support. Presidents have their own views, but Congress is the core. So to pick a fight with members of Congress, which is going to force half of Congress to rally to their defense is really foolish.”
While support for Israel among congressional Democrats remains strong, polls show that support has long been slipping among Democratic voters. Matt Brooks, executive director of the Republican Jewish Coalition, which aims to woo Jews to the Republican Party, said it was wrong to lay the dwindling Democratic support at the feet of Mr. Trump and Mr. Netanyahu.
He noted that just recently, Senator Bernie Sanders of Vermont, who is running for the Democratic presidential nomination, accused the Netanyahu government of “racism” and proposed using American aid to Israel as leverage to change its policies. By contrast, he said, Mr. Trump has moved the American embassy to Jerusalem and recognized Israel’s sovereignty over the Golan Heights — moves that were welcomed by Israel.
“When you have a leading Democratic presidential candidate like Bernie Sanders who can call the prime minister of Israel a racist and nobody says anything, you tell me who’s responsible for it,” Mr. Brooks said. “We have a president who is the most pro-Israel president ever in history.”
As Mr. Trump has sought to portray himself and his fellow Republicans as the only party for American Jews, Democrats in Congress have gone to great lengths this year to show their support for the Jewish state, and to isolate Ms. Tlaib and Ms. Omar, whose public support for the Boycott, Divestment and Sanctions movement against Israel, which aims to pressure Israel to end its occupation of the West Bank, is the reason they were not allowed to visit in an official capacity.
Last month, the House overwhelmingly passed a resolution condemning the movement, known as B.D.S. After Ms. Omar criticized AIPAC in remarks that were widely construed as anti-Semitic, Democratic leaders called on her to apologize — she did — and the House later passed a resolution condemning hatred of any kind.
But the Israeli government’s decision to bar the two women has even their Democratic critics rallying around them. It has also energized the Democratic left, which is already deeply critical of the Netanyahu administration, and thrust Israel policy into the center of the 2020 electoral debate.
“Trump and Netanyahu are enabling one another to make Republicans the go-to party on Israel and Democrats the devil, eroding the bipartisanship that is so critical to the U.S.-Israel special bond,” said Aaron David Miller, a veteran Middle East negotiator for both Republican and Democratic administrations. “It is not yet fatal. But a few more years of the Trump-Netanyahu experience and it may well be.”