Sheldon Adelson gave half of June donations to pro-Romney super PAC

— -- Restore Our Future, a super PAC supporting Mitt Romney's campaign for president, raised about $20 million in June, more than three times the amount pulled in by the main super PAC behind President Barack Obama's re-election bid.

Just under half of the donations came from Las Vegas casino magnate Sheldon Adelson and his wife, who each donated $5 million apiece to the effort.

The group also received gifts of $1 million or more from a handful of sources, including Boston-based private equity leader John W. Childs, Texas-based real estate investor Harlan Crow and businessman Bill Koch. Foster Friess, who supported former Pennsylvania Sen. Rick Santorum's Republican primary bid, gave $200,000.

So far this calendar year, Restore Our Future has raised $52 million and has $23 million left in cash on hand, according to financial disclosures filed with the Federal Election Commission Friday. The June haul is a significant boost from May, when the group raised $4.9 million.

Priorities USA Action, which supports Obama, took in $6.1 million in the same month.