WASHINGTON — Charities and nonprofit organizations are worried that new limits on tax deductions for high earners will hurt donations just as charitable giving is starting to rebound from the depths of the recession.

Experts doubt the new limits on deductions will have much impact on giving, but some major nonprofit organizations fear they are a sign that the charitable deduction is no longer sacrosanct on Capitol Hill, just as Congress is promising a broader effort later this year to overhaul the tax code.