new york | Birthright Israel is slashing the number of participants on its summer trips this year because of funding problems.

Some 3,500 participants, all but 500 of whom will come from North America, is all “we can manage in light of all the uncertainties,” Michael Steinhardt, a key Birthright Israel benefactor, said.

This winter, Birthright Israel took more than 10,000 youths to Israel, including 8,000 from North America.

Now in the last of its five pilot years, the free trip to Israel for 18-to 26-year olds has taken about 60,000 diaspora youths to the Jewish state.

The future of the program — hailed as a revolutionary way to strengthen Jewish identity among diaspora youths, giving many of its participants Zionist ideals and Jewish values — is uncertain.

When the program began, Jewish communities worldwide — largely the North American Jewish federation system — the Israeli government and a group of 14 philanthropists had agreed to divide evenly the funding for the $210 million, five-year program.

But some of those sponsors have fallen short on their funding responsibilities.

For many of Birthright Israel’s advocates, Israel’s stance on the program is frustrating.

A spokeswoman for Benjamin Netanyahu, whose finance ministry constructs the budget, explained that “due to the cutbacks in the government budget, they had to cut back also in this project.”

But despite “budget distress,” Israel donated a symbolic level of funding — about $450,000 — to express its appreciation for the program, she said. Israel also committed to restore full funding in 2005.

Still, the Birthright program could be on shaky ground.

Steinhardt sums up the scenario like this: some progress in shoring up funds from the federations, a commitment by a “fair number of the philanthropists” to continue funding the program, but no assurances from Israel.

“We are going to look at the program in the spring of this year and decide where we go,” he said.