Tuesday’s primary election stunner in Virginia leaves a number of well-heeled interest groups walking away empty-handed after spending tens of thousands of dollars on what was supposed to be a sure thing. That may not, however, be the case for Eric Cantor, who announced Wednesday that he would soon be stepping down from his perch as House Majority Leader.

Campaign finance rules allow plenty of leeway for Cantor, a top GOP fundraiser whose once-bright political career was cut short by tea party insurgent Dave Brat, to spend the money left in the leadership PAC.

Cantor’s leadership committee, Every Republican Is Crucial (ERIC) PAC, had nearly $580,000 on hand at the beginning of May. While ex-members of Congress can’t spend campaign committee funds for personal use, the same prohibition does not apply to leadership PACs.

The majority leader’s more than half-million nest egg gives him by far and away the biggest potential windfall among this year’s departing members of Congress.

Of course, the potential upside for the PACs and business interests that poured tens of thousands of dollars into Cantor’s campaign is not so clear, after they made the wrong bet in an election that college professor Brat won by ten points.

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No group had more invested more in Cantor than the American Chemistry Council, the chemical manufacturers giant that counts major corporations like Eli Lilly, ExxonMobil Chemical, and DuPont among its members. The trade group spent a little over $308,000 on a television ad touting the congressman as a friend of small business.

Cantor’s loss means the ACC loses a valuable ally as it wages a multimillion dollar lobbying effort aimed at clean air, water and greenhouse laws.

The Chemistry Council, of course, was not the only organization to pick the losing horse.

Cantor raised more than $5.7 million by Tuesday’s primary and the contributions kept flowing until the bitter end. In the last 20 days of the campaign, his campaign raised $313,700 in large contributions of $1,000 or more. That’s more than what Dave Brat’s campaign raised in the entire primary ($230,000).

Moreover, most of the $32,600 in last-minute big checks that Cantor did get from within his state came from outside his district. As the table below shows, the Washington suburbs ponied up far more than the congressman’s home base in Richmond.

Executives from Altria, Berkshire Hathaway and the Heritage Provider Network, California-based healthcare group, each contributed $50,000 to the Cantor Victory Fund, a joint committee that raised money for Cantor’s campaign, leadership PAC, the local party committee and the NRCC.

A host of different political action committees combined to contribute over $2.2 million. Though Cantor is not a member of any committees, his high rank makes him a popular target for a diverse set of business interests. John Deere, Hewlett Packard, Halliburton and United Airlines are just a few of the groups that chipped in to keep Cantor in office, each giving $5,000. And while they may have had a vested stake in the outcome of the Seventh District’s elections, most of these committees hail from outside of Virginia.

In fact, 71 percent of the itemized donations ($200 or more) that went to Cantor’s campaign kitty, came from outside the Old Dominion State.

Brat, in stark contrast to his opponent, relied entirely on individuals to finance his campaign. The Friends of Dave Brat committee did not report a single itemized PAC contribution.