By Steve Holland and Emily Flitter
WASHINGTON (Reuters) - Democratic presidential front-runner Hillary Clinton attacked Republican Donald Trump on Monday for taking a neutral stance toward Israeli-Palestinian peace efforts, in a preview of a possible general election battle between them.
On a day Trump was visiting Washington, Clinton told the American-Israeli Political Action Conference (AIPAC) that Trump's neutral stance in the search for peace between Israel and the Palestinians would be dangerous for Israel, a stalwart U.S. ally in the Middle East.
"America can't ever be neutral when it comes to Israel's security and survival," Clinton told the pro-Israel lobbying group, without mentioning Trump by name. "Anyone who doesn’t understand that has no business being our president."
Trump, the Republican front-runner, was to address the AIPAC conference later in the day, along with his Republican rivals, U.S. Senator Ted Cruz of Texas and Ohio Governor John Kasich. Clinton's challenger, U.S. Senator Bernie Sanders of Vermont, was not appearing at the event.
Trump has drawn fire for his position on Middle East peace negotiations. The New York billionaire has described himself as extremely pro-Israel but has said he would take a "neutral" stance in trying to negotiate an elusive peace settlement between Israel and the Palestinians.
Trump's critics have said a neutral position could harm long-standing U.S. support for Israel. Clinton said she would make it a priority if elected to preserve the U.S.-Israeli relationship, ensuring Israel has a qualitative military edge.
Clinton also took aim at Trump's vow that, if elected, he would deport illegal immigrants and bar Muslims temporarily from entering the United States.
She noted an incident during the 1930s, when the United States initially refused entry to a shipload of Jews trying to escape Nazi tyranny.
"We've had dark chapters in our history before," Clinton said. "We remember the nearly 1,000 Jews aboard the St. Louis who were refused entry in 1939 and sent back to Europe. But America should be better than this. And I believe it is our responsibility to say so.
"If you see bigotry, oppose it, if you see violence, condemn it, if you see a bully, stand up to him," she said.
Trump was in Washington for a meeting with a variety of Republicans organized by his top backer in the capital, U.S. Senator Jeff Sessions of Alabama. He also planned a news conference at the hotel he is building at the Old Post Office on Pennsylvania Avenue.
Trump's rise has alarmed establishment Republicans who have tried in vain to stop him. Their best hope of derailing his insurgent candidacy is to stretch the contest out and deny him the 1,237 delegates needed to formally win the party's presidential nomination.
Such an outcome would mean that the nominee for the Nov. 8 election would be decided at the party's convention in Cleveland. Despite the possibility of turmoil at the July 18-21 event, Republican Party Committee Chairman Reince Preibus predicted a "fun" convention.
Priebus, on CNN, shrugged off Trump's comment last week that riots would break out if he is denied the nomination.
“I guess I don't put it at the level of a warning to us. He obviously said yesterday he doesn't believe that. ... We're prepared for all contingencies. We'll have over $50 million in security at the convention. ...
"So we'll be prepared. It'll be fine, and I guarantee you we'll have a good time, and it'll be a fun convention in Cleveland," Priebus said.
(Additional reporting by Susan Heavey and Mohammed Zargham)