Donald Trump's past contradictory statements on Israel have raised questions about his ability to handle foreign relations — especially as he moves closer to the Republican presidential nomination.

Whether he can sharpen his rhetoric will be the question Monday evening when he addresses the annual policy conference of the American Israel Public Affairs Committee, or AIPAC.

Like many Republicans, Trump is often quick to praise Israel. At a Republican primary debate in Florida earlier this month, Trump said there was "no one more pro-Israel" than him.

Trump was asked about previous statements he'd made about the Israeli-Palestinian conflict. At a forum in February, Trump said he'd like to remain neutral between the two parties, sparking criticism from his rivals for the GOP nomination, who said he was not supporting Israel strongly enough.

Asked to clarify at this month's debate, Trump said, "I'm a negotiator. If I go in, I'll say I'm pro-Israel, and I've told that to everybody and anybody that would listen. But I would like to at least have the other side think I'm somewhat neutral as to them so that we can maybe get a deal done."

While the U.S. is officially neutral, Trump's position is a departure from his party's typical rhetoric stressing support for Israel.

It's not the first time he has stumbled on issues important to many Jewish voters. Last month, Trump seemed to hesitate when asked to repudiate the support of radio host David Duke, before clarifying that he disavows the former KKK leader.

Back in December, during an appearance with the Republican Jewish Coalition in Washington, D.C., Trump was asked if he'd support recognizing Jerusalem as Israel's capital. He said he wanted to wait to comment until after a trip to Israel to meet with Prime Minister Benjamin Netanyahu, eliciting boos from the audience. That meeting was canceled after Netanyahu condemned Trump's proposal to ban all Muslims from entering the U.S.

In addressing AIPAC, Trump will face a sophisticated audience on Middle East policy, said Josh Block, president and CEO of The Israel Project and a former AIPAC spokesman.

"This speech is an important opportunity for him both to pivot to a more serious approach on foreign policy, and to provide the kind of specifics that people are looking for from each of the candidates," Block said.

Trump's critics have questioned his larger grasp of foreign policy, and his fitness to handle volatile international negotiations. Thomas Donnelly, a research fellow at the conservative American Enterprise Institute, said "the rest of the world is quaking" at the idea of a Trump presidency.

Donnelly said Trump's speech will be closely watched by observers wondering what such a presidency would mean for foreign policy.

"It's very difficult to regard the series of declarations and expressions of anger that Trump has made as anything so coherent as a policy. It's more an attitude," Donnelly said, adding that Trump could win over the audience if he adheres to standard Republican positions on support for Israel.

Last week on MSNBC, Trump was asked where he's turning for advice on thorny international issues.

"I'm speaking with myself, number one, because I have a very good brain," Trump said. "So I know what I'm doing, and I listen to a lot of people. I talk to a lot of people."

In a statement to NPR, the Republican front-runner's campaign said he'll be announcing his foreign policy advisers in the near future.

Even Trump's supporters, like neurosurgeon and former presidential candidate Ben Carson, have noted that Trump is not always steady when addressing policy.

Carson said there are "two different Donald Trumps" when he endorsed Trump this month, a statement Trump later said he "probably" agrees with.

"There's the one you see on the stage, and there's the one who's very cerebral, sits there and considers things very carefully; you can have a very good conversation with him. And that's the Donald Trump that you're gonna start seeing more and more of right now," Carson said.

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