JERUSALEM—Mitt Romney raised more than $1 million at a campaign fundraiser here on his way out of Israel.

At least 40 donors paid between $25,000 and $50,000 apiece to attend a breakfast with Romney at a hotel—including Las Vegas casino magnet Sheldon Adelson, who has contributed more than $20 million to Republicans and conservative super PACS so far this election cycle. Of that total, $10 million went to Restore Our Future, a political committee backing Romney's bid for president.