The biggest losers in the US midterm elections? Republican mega-donors

Donors like Peter Thiel poured millions into candidates that no amount of money could sell to voters while Mehmet Oz self-funded a failed run

With the power balance in Congress at stake in this year's midterm elections, the GOP money machine kicked into high gear. Spending on advertisements and drumming up votes was fueled by hundreds of millions of dollars from the party's mega-donors and Super Pacs. Many donors' spending figures marked new records.

Their return on investment, however, is probably not what they had hoped: some donors who spent eight figures notched zero wins in the Senate, while others spent far more money on losing candidates than winners. In the midterms, some of the biggest losers were Republican donors.