A host of Israeli leaders and pro-Israel voters had long been advocating for the decision that President Trump announced on Wednesday, which recognized Jerusalem as the capital of Israel and began the process of relocating the U.S. Embassy from Tel Aviv. The fact that the controversial decision was carried out by a Republican president is indicative of the dramatic change in the GOP’s position on Israel since Israel was founded.

The Republican party has moved from not supporting Israel enough, in the eyes of many Jewish Americans, to backing policies that now go further than the positions espoused by many Jewish voters — but are in keeping with the views of evangelical voters. As bipartisan support for Israel erodes, the controversial move risks further accelerating a growing party split.

Jewish Americans have for decades voted overwhelmingly for the party of Franklin D. Roosevelt, who defeated Hitler and was beloved for his New Deal policies, and Democrats were the party that championed Israel when it was first established in 1948. In contrast, Israel and the Republican Party had a tumultuous relationship early on. In the 1950s, following Democratic President Harry Truman’s recognition of the state of Israel, support for the country within the Republican Party and the conservative movement was highly limited. Since the vast majority of Jews were Democrats, there was little push from within the GOP to support the newborn nation.

The GOP’s domestic and foreign policy orientation in that era didn’t strengthen the case for the party supporting Israel either: The Middle Eastern country’s socialist bent scared away the anti-communists in the Republican Party, and the GOP’s foreign policy pragmatists were concerned that support for Israel would undermine America’s ties with the increasingly important oil-producing nations in the Middle East, many of which had fought against Israel when it declared independence.

Typical of Republican sentiment at the time were the critiques of Israel published in The National Review. Political philosopher Leo Strauss went so far as to write a letter in 1956 to complain. The journal’s editor, Willmoore Kendall, acknowledged there was an “anti-Israel bias among my colleagues, and in Right-wing circles in general.”

Although Kendall emphasized that he did not believe that anti-Semitism was behind that bias, successive Republican presidents were eyed warily by many pro-Israel Jews well into the George H.W. Bush administration. Richard Nixon, though he supported Israel in the 1973 Arab-Israeli War, was believed to be a raging anti-Semite (a belief that was vindicated when tapes of his conversations were released decades later), and even Ronald Reagan’s support for Israel was questioned when he penalized the Jewish state for its bombing of Iraq’s nuclear reactors.

By the end of the 1990s, though, attitudes began to shift, due largely to world events, changes in a major GOP constituency and changes in the Jewish community. Israeli politics also played a role.

The most pronounced turning point in GOP voters’ support for Israel came after 9/11, as increased U.S. military involvement in the Middle East resulted in more pro-Israel policies percolating into the Republican agenda. Israel was struggling with its own upswing in terrorist attacks, so many influential conservatives saw new relevance in Samuel Huntington’s model for a clash of civilizations in which Israel and the United States were aligned as members of “the West,” in opposition to other cultures — in this case, Islam.

At the same time, the Jewish community was increasingly made up of baby boomers who had rejected their parents’ affinity for the Democratic party and found themselves at home in Republican administrations seeking to project American power and values. They also took on key roles in campaigns, both as donors and advisers, which allowed them to bring more attention to their top issues.

Starting as early as 2004, casino mogul Sheldon Adelson, for example, began to throw his financial weight behind Republican candidates, whom he said better represented his values — and especially his support for Israel. Writing in The Wall Street Journal in 2012, Adelson explained that he had left the Democratic Party because it had changed, becoming home to “a visceral anti-Israel movement among rank-and-file Democrats.”

It can be argued whether Adelson’s assessment was fair, but public opinion polls over the last decade have suggested that Democrats’ support for Israel has cooled even as support among GOP voters increased.

In some ways, Israeli politics themselves have contributed to the Republican Party’s shift in views. Since the mid-1990s, the Israeli right wing has been dominated by Benjamin Netanyahu, who served as prime minister for part of that decade and now holds the office again. Netanyahu broke away from the traditionally statist Israeli right to support economic policies that lined up with those of U.S. economic neoliberals. He shares a major supporter — Adelson — with many top U.S. Republicans, and he has cultivated personal relationships with U.S. Republican leaders.

When Republicans now look to Israel, they see in Netanyahu a leader cut from a similar ideological cloth to many of their own representatives — not just in terms of foreign policy beliefs but also in economic positions, one who shares a Republican skepticism of the welfare state and embraces free markets. A 2015 poll found that Republicans ranked Netanyahu alongside Ronald Reagan as the “national or world leader you admire most.” Netanyahu’s headline-grabbing tussles with then-president Barack Obama, which alienated many Jewish Democrats, only served to raise his profile among Republicans.

But perhaps most importantly, since the 1990s, evangelical Christians have come to represent one of the strongest and most hawkish pro-Israel demographics within the Republican party. Until the 1970s, evangelicals tended to avoid direct involvement in political activism. When Jerry Falwell’s Moral Majority emerged at the end of that decade, fusing religion and politics, Israel wasn’t the top issue. But Falwell did emphasize that evangelicals — a group that at times had had mixed attitudes toward Jews and Israel — should understand their theology as strongly backing Israel. (Many pro-Israel evangelicals believe that Israel is essential to the second coming of Jesus or that they are following a literal interpretation of a Biblical injunction that God will bless those who bless Israel and curse those who curse Israel.) In the early ’80s, support for Israel dovetailed with strong anti-communism, as evangelicals slammed the Soviet Union for maintaining harsh policies restricting Jewish and Zionist activities.

Today, Israel is a voting priority for many evangelicals. A 2015 poll noted that 64 percent of evangelical Christian Republicans say that a candidate’s stance on Israel matters “a lot,” compared with 33 percent of non-evangelical Republicans and 26 percent of all Americans.

And evangelical Christian voters, unlike Jews, represent a significant percentage of Republican voters. Some 26 percent of the electorate identified in the 2016 elections as born-again or evangelical Christian, and 81 percent of them voted for Trump over Hillary Clinton. Capturing evangelical support is essential for Republican candidates; as of 2014, evangelical and born-again voters represented the plurality (45 percent) of voters who are Republican or who lean Republican.

Propelled by evangelicals, the GOP has in many cases become more hawkish than most U.S. Jews. While the Republican Party has notably turned away from traditional U.S. support for a two-state solution, which would establish a Palestinian nation alongside Israel (only 23 percent of evangelicals polled in 2017 agreed that Israel should agree to the creation of a Palestinian state), the majority of U.S. Jews believe that Israel and an independent Palestine can coexist peacefully. Although members of the Trump administration — most notably, perhaps, Mideast negotiator and Trump son-in-law Jared Kushner — support Israeli construction in the disputed West Bank, only 17 percent of U.S. Jews believe that Jewish settlements in the area help Israel’s security. An election-night poll of Jewish voters in 2016 by the dovish J Street suggested that Israel isn’t even really the primary voting issue for many Jews: Only 9 percent listed it as one of their top two voting priorities.

In fact, it is the pro-Israel evangelical community — and particularly Pastor John Hagee’s Christians United for Israel — that has mobilized alongside hawkish pro-Israel Jews to push for a change of U.S. policy on Jerusalem. Hagee, whose organization boasts over three million members, has been pushing Trump to move the embassy since the 2016 campaign season, to prove the president’s commitment to evangelical values.

The evangelical community is unusual in their support for moving the embassy to Jerusalem. A November poll indicated that 63 percent of Americans oppose the move, but 53 percent of evangelical voters support it.

Whatever GOP constituency pressed for the move the most, what matters in the end is that they succeeded. Though Democratic and Republican presidential candidates alike have long promised to recognize Jerusalem as Israel’s capital and move the U.S. Embassy there, none who won the office ever did so — until Trump.

But the president is not widely embraced by Jews as a whole (while some 50 percent of Orthodox Jews voted for Trump, the two larger streams of U.S. Judaism — Reform and Conservative — opposed Trump), so it remains to be seen whether his recognition of Jerusalem increases Jewish affinity for the Republican Party. That outcome will surely be influenced by what happens next.