The U.S. must never be “neutral” about defending the State of Israel, or consider its relationship with Israel negotiable, Democratic presidential candidate Hillary Clinton said on Monday.

Speaking at AIPAC’s annual policy conference at the Verizon Center in Washington, D.C., Clinton drew a sharp contrast with Donald Trump, the Republican presidential front-runner, on Israel and foreign policy.

“It would be a serious mistake for us to abandon our responsibilities or cede mantle of leadership for global peace and security,” said Clinton. Adding, “Candidates who think the U.S. can outsource Middle East security to dictators are dangerously wrong.”

According to the former Secretary of State, the next commander-in-chief must be a steady hand, not unpredictable, when it comes to standing by America’s allies like Israel. Clinton made reference to Trump’s recent comments in which he suggested he would be neutral on the Israeli-Palestinian conflict to broker a peace deal.

“We need steady hands and not a president who says he’s neutral on Monday, pro-Israel on Tuesday, and who knows what on Wednesday,” she said to loud applause. “Israel’s security is non-negotiable.”

“The U.S. can never be neutral when it comes to Israel’s security and survival. Some things aren’t negotiable,” Clinton added.

Vice President Joe Biden, who spoke at Sunday night’s general session, also made an unsubtle reference to Trump by saying, “The future belongs to the bridge builders, not the wall builders.”

Trump is expected to address AIPAC in the evening. In a preview of the speech on Sunday, Trump dropped the word “neutral,” buy reiterated his eagerness to broker a peace settlement between Israel and the Palestinians. “I think making a deal would be in Israel’s interests,” he said on ABC’s “This Week” program. “I’ll tell you what, I don’t know one Jewish person that doesn’t want to have a deal, a good deal, a proper deal, but a really good deal. And I don’t know any Jewish people that don’t want to make it. They’d all love to see a deal made.”

In her speech, Clinton said that one of three tests the next president must be ready for when he/she steps into the Oval Office will be to keep us safe. As such, the U.S.-Israel relationship and U.S. leadership in the Middle East will be critical in passing that test. She promised to invite the Israeli Prime Minister in her first month in office.

“Let us never be neutral or silent in the face of bigotry. Together let’s defend the shared values that already make America and Israel great,” Hillary concluded her speech.