A growing partnership between Israel and Arab leaders arrayed against the threat of Iran likely made it easier for President Trump to recognize Jerusalem as the capital of Israel, according to a leading Republican senator.

“The Arab world has changed over time ... and it is now in a situation where the greatest threat to stability and security in the Middle East is Iran,” Sen. Tom Cotton, R-Ark., told the Washington Examiner. “And therefore you have a strong alignment of interests between Arab nations and Israel. While they might not prefer this choice [to recognize Jerusalem as Israel's capital], they understand that their main enemy — that Israel shares — is Iran.”

Trump is expected to announce the move Wednesday afternoon, a decision made over the objections of the State Department and the Pentagon, two sources close to the White House told the Washington Examiner. Opposition from allies in the Arab world has long impeded U.S. proponents of such a shift, but analysts and lawmakers believe that the need for Israel and Arab nations to cooperate against Iran’s play for regional hegemony gives Trump new room to maneuver.

“It’s the right decision,” Cotton said. “It’s an overdue decision.”

Secretary of State Rex Tillerson and Defense Secretary Jim Mattis disagreed, according to two sources close to the White House. They held to the traditional view, echoed in Europe and across the Middle East, that such a move would hurt the Middle East peace process and risk a renewal of tensions between Israel and Arab allies of the United States.

“Having the consistent refrains from many people who have been long involved at the State Department and at the Department of Defense object to this move on behalf of the president is not a surprise,” Rep. Mark Meadows, R-N.C., a member of the Foreign Affairs Committee who has developed a rapport with Trump while leading the House Freedom Caucus, told the Washington Examiner. “But we also have to recognize that, going back decades, those policies have not produced any lasting peace accord on behalf of Israel and its neighbors.”

The Wednesday announcement will be the second time in two months that Trump has rebuffed Mattis and Tillerson’s preferences on Middle East policy after he denounced the Iran nuclear deal in a high-profile speech in October. The recurrence reflects a degree of cooperation between the two to a degree unusual for the nation’s top diplomat and the nation's top military leader.

But the latest disagreement reflects the State Department’s standard skepticism of moving the embassy to Jerusalem, rather than friction with Trump's team, it was suggested.

"The State Department is just inherently anti-Israel, [though] I don't mean to say they're anti-Semitic," said a senator close to the president and the administration. "if you're the secretary for near east affairs . . . What do you hear all day long? All day long, you hear that Israel is the problem.”

That chorus has quieted with the rise of Iran, according to another analyst who has worked with the Trump administration. “I am right now not convinced that the Arab world sees the Palestinian issue as a core national interest,” the Foundation for Defense of Democracies Jonathan Schanzer told the Washington Examiner. “The threat of Iran is a core national interest ... And Israel is aligned with them on these issues.”

That recognition may have softened some of the pushback from Tillerson and Mattis.

“It's not like they threw a fit. It's just what they assess — for their purposes it makes shit more complicated,” the source told the Washington Examiner. “The State Department prefers when everyone's happy, and this will make people unhappy. The [Defense Department] prefers when everyone's calm, and this will rile up some people. All of the departments assured the president that... there's nothing they can't handle.”

Trump and others who support recognizing Jerusalem as Israel’s capital have a role to play in minimizing the provocation that could be caused by the move. Cotton emphasized that nothing about Trump’s announcement should be construed as preventing the formation of a Palestinian state with a capital in East Jerusalem, a deal that negotiators have long hoped to strike.

“It does not prejudge any other issued related to Jerusalem about where the Palestinian capital will be based there or what exact lines might appear,” Cotton said.