For two years, Jewish conservatives have had a standard response for members of their community who didn’t understand how anyone could support President Donald Trump.

In spite of his manifest faults, his administration has arguably been the warmest supporter of Israel in its 70 years of existence. By appointing a Middle East peace team composed of Orthodox Jews who were ardent supporters of the Jewish state and the government led by Prime Minister Benjamin Netanyahu, breaking with decades of policy tradition and moving the U.S. embassy to Jerusalem and withdrawing from the Iran nuclear deal, Trump fulfilled all the wishes of Jewish Republicans and most of the pro-Israel community - and then some.

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In that sense, Jewish supporters of Trump have been very much like the overwhelming majority of Republicans. Far from them abandoning their conservative principles for his sake, on policy, the ex-liberal Trump has largely done exactly what most in the GOP wanted on a host of issues including judicial nominations, tax reform and deregulation.

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Open gallery view US President Donald Trump shakes hands with Israel's Prime Minister Benjamin Netanyahu during a visit to the Israel Museum in Jerusalem on May 23, 2017 Credit: MENAHEM KAHANA/AFP

That is why, no matter what else has happened, and as the rest of the country’s dismay at his coarsening of public discourse and the various scandals that have engulfed the White House grew, Trump’s popularity among Republicans has remained at close to 90 percent.

The question is: can his support from Jewish conservatives outlive a policy betrayal on a key issue?

With Trump’s withdrawal from Syria, a measure that seems to isolate Israel and strengthen Iran, we’ll have the opportunity to test the loyalty of Jewish conservatives to the president.

The ultimate consequences of a move that reminds his supporters that there was always a great deal in common between Trump’s approach to Syria and Russia and that of President Barack Obama are still a matter of conjecture. But there’s little doubt that this is the moment when pro-Israel activists holding their nose about Trump’s character will be sorted out from the hard-core true believers.

Most Jewish support for Trump must be seen not so much as the product of the sort of personal loyalty that has fueled his populist base but a function of the shift among the two parties on Israel.

As Republicans have become a lockstep pro-Israel/pro-Netanyahu party because of the influence of Christian conservatives and Democrats became increasingly split on the Jewish state, Jewish support for the GOP has largely broken down on ideological and denominational lines.

Open gallery view An Israeli soldier stands near the Quneitra crossing in the Golan Heights on the border line between Israel and Syria, October 15, 2018 Credit: \ Amir Cohen/ REUTERS

Approximately 24 percent of Jews voted for Trump in 2016. An American Jewish Committee survey taken in 2018, after the announcement of the Jerusalem move and when the clear shift from Obama’s policy of pressure to Trump’s largely uncritical approach was already apparent, still showed 57 percent of American Jews disapproved of his handling of U.S.- Israel relations with only 34 percent approving. The same poll produced a 71-24 percent result on (dis)approval of the Trump presidency.

Since the farther right you go on both the political and religious spectrum, the more likely U.S. Jews are to identify Israel as the most important issue for them, Trump’s ability to please the pro-Israel community explains why so many of them believe his policies vindicates their votes for him. It also explains why a disproportionate percentage of Jewish Trump supporters are Orthodox.

Most modern Orthodox and secular conservative Jews are part of the same middle and upper middle class and educated demographic groups that have generally produced fervent adherents of the anti-Trump resistance. But Trump’s backing for Israel gives them an ironclad rationale for voting Republican.

As has largely been the case with the Israeli government itself, reactions to the decision have been muted so far. AIPAC’s non-committal statement sought to avoid criticism, while noting the dangers.

It has also quietly retweeted two highly critical tweets on the decision – one from a Republican congresswoman and one from a Democratic senator.

But the silence from groups like the Republican Jewish Committee, The Israel-American Council and Stand With Us, which lean far more towards Trump than the mainstream lobby, is telling.

The president’s instinctual distrust of the foreign policy establishment led him to embrace stands pro-Israel voters liked on the peace process, Jerusalem and Iran. But those same instincts have now caused him to reject the advice of mainstream conservatives serving in his administration like outgoing UN Ambassador Nikki Haley, a huge favorite in the Jewish community.

So long as the blowback from Syria remains theoretical, rather than producing imminent peril for Israel, it will be possible to keep arguing that Trump’s support for Israel is unquestioned. But if Trump sticks to his more isolationist instincts and leaves Iran a clear field in Syria, the division among his Jewish supporters will speak loudly about the power of partisanship.

Open gallery view US President Donald Trump receives applause after signing the "First Step Act" and the "Juvenile Justice Reform Act" at the White House in Washington, DC, on December 21, 2018 Credit: AFP

With American Jews reflecting the same red/blue divide that has split all Americans between those who trust Trump critics at The New York Times, and those who listen to the talking heads on Fox News, there is always going to be a die-hard faction that will stick with Trump no matter what he does on Israel or anything else.

But the more he resembles Obama, and if a worsening of Israel’s already worrisome security dilemma in the north is seen as stemming from Trump’s retreat, Jewish support for Trump, even among Republicans and Orthodox Jews, will begin to erode.

It may be that nothing will erase the embassy move in the minds of litmus test pro-Israel voters. But while Jewish Democrats will stick to their party, no matter what its leader does with regard to Israel, Jewish Republicans have repeatedly proved - as they did in 1992, when President George H.W. Bush wound up getting only 11 percent of the Jewish vote after a stand-off with Israel over loan guarantees - they won’t vote for anyone who is perceived as less than supportive of the Jewish state.

Seen in that light, no one should doubt that Trump’s percentage of Jewish support - especially among those in the educated classes, whose cultural distaste for Trump’s populism and his right-wing base might otherwise lead them to defect from the GOP - could drop precipitously if his Syria decision is a harbinger of other strategic moves that will distance him from Israel.

Jonathan S. Tobin is editor in chief of JNS (the Jewish News Syndicate) and a contributing writer for National Review. Twitter: @jonathans_tobin