Republican Party split over whether Trump should involve US in Israel-Iran conflict

President Donald Trump's consideration of bringing the United States into Israel's conflict with Iran has reignited tensions inside the Republican Party and Trump's own base, pitting traditional GOP hawks against prominent anti-interventionist voices in the party.

Trump said Thursday, via White House press secretary Karoline Leavitt, that he believes there's a "substantial chance of negotiations" between Israel and Iran, and will make a decision on escalations within the next two weeks.

Trump has repeatedly criticized American involvement in wars overseas and vowed to shift the focus inward, but as he weighs whether the U.S. will be involved in the conflict between Israel and Iran, some of his supporters have accused him of going back on his anti-interventionist stance.

"Among the America First base -- which is the core of his base -- there is tremendous anger and a severe sense of betrayal," Trita Parsi, co-founder and executive vice president of the noninterventionist foreign policy think tank Quincy Institute, told ABC News Wednesday. "This is exactly the type of foreign policy Trump had promised to end, not boost."

Marjorie Taylor Greene, a key supporter and Trump ally on Capitol Hill, also dismissed the more hawkish members of her party as not authentically "MAGA."

"Anyone slobbering for the U.S. to become fully involved in the Israel/Iran war is not America First/MAGA," Greene wrote in a Facebook post on June 15. "We are sick and tired of foreign wars. All of them."

Some Republicans are attempting to preempt military action through legislative means. Republican Rep. Thomas Massie announced on Tuesday that he had introduced a bill with Democratic Rep. Ro Khanna to prevent Trump from involving the U.S. army in "unauthorized hostilities" in Iran. Twenty-three representatives have now signed onto the bill -- including many from the progressive "squad" of the Democratic party.

"This is not our war. Even if it were, Congress must decide such matters according to our Constitution," Massie wrote in his X post announcing the bill, which Democratic Rep. Rashida Tlaib said she would "look forward to supporting."

Justin Logan, director of Defense and Foreign Policy Studies at the libertarian Cato Institute, told ABC News that some Republicans were pushing back against U.S. involvement because they "realize that there's a real prospect that this could cave in their political coalition and do great damage to the Republican Party."

"There's not a lot of evidence that the MAGA base is excited about another major war in the Middle East," Logan said. "I think the president, this is his last term, he's listening to some people that have some wild and crazy ideas about U.S. policy in the Middle East, and he doesn't share their concern."

Logan said while the bill was a "noble" effort, he thought it likely would not hinder U.S. involvement if Trump decided to take that course.

"If he wants it, the president will get war," he said.

Other, more hawkish Republicans have embraced Trump's consideration of openly aiding Israel's campaign.

Republican Sen. Lindsey Graham said on Fox News earlier this week that Iran is "an extremist regime that, if given the chance, would wipe Israel off the map and then come for us," and expressed his support for the U.S. ensuring Iran would not obtain a nuclear bomb.

On Capitol Hill Wednesday, Graham told ABC News he believed Trump was "very steady" and endorsed the use of force if diplomacy talks fall through.

"He's intent on making sure that Iran doesn't have a nuclear weapon," Graham said of Trump. "Either you want them to have a nuclear weapon, or you don't. And if you don't, if diplomacy fails, you use force."

Republican Sen. Rick Scott also said earlier this week that he trusts "that President Trump will do the right thing."

And Vance has expectedly backed Trump's authority to make the final call.

"POTUS has been amazingly consistent, over 10 years, that Iran cannot have a nuclear weapon… And he said repeatedly that this would happen one of two ways--the easy way or the 'other' way," he wrote on X Tuesday.

Former Trump advisor Steve Bannon told a group of reporters Wednesday morning that it would be a mistake for the United States to get involved in direct military action against Iran, and expressed confidence that Trump's base would support a decision either way.

"I will tell you, if the president as commander in chief makes a decision to do this, and comes forward and walks people through it, the MAGA movement -- you'll lose some -- but the MAGA movement, the Marjorie Taylor Greenes, the Matt Gaetzes, we will fight it up to the end, to make sure he's got information, but if he has more intelligence and makes that case to the American people, the MAGA movement will support President Trump," Bannon said at a Christian Science Monitor event.

A Fox News poll published Wednesday found that a majority of registered voters believe Israel's strikes on Iran's nuclear program would result in more danger, but nearly three out of four Americans also believe Iran poses a national security threat to the U.S.

ABC's Allison Pecorin and Brittany Shepherd contributed reporting.