The most expensive congressional campaign in history ends tomorrow in a suburban district north of Atlanta and while the winner is yet to be determined it’s already clear that he or she will take office beholden to an array of big money donors.

Democrat Jon Ossoff and Republican Karen Handel and a variety of party and independent groups have put an eye-popping $55 million into the race, according to an analysis of campaign finance reports by MapLight, a California-based non-profit group that studies money in politics.

Roughly half of that money – about $27 million – came from independent, “dark money” groups, so-labeled because they operate under a section of federal tax law that allows them to conceal their donors. MapLight says $18.5 million of that went to boost Handel, while $8.2 million benefitted Ossoff.

Handel also has gotten more help from Republican Party groups – $6.7 million – than Ossoff has received from Democratic committees – $5.4 million.

Ossoff held a substantial edge in contributions from individual donors however. He has raised and spent $23 million from them, including more than $15 million that arrived in checks of $200 or less. That compared to $4.3 million in individual gifts to Handel, who raised just $1.6 million from small-dollar donors.

If Ossoff wins tomorrow, and several recent polls give him a slight lead, he’ll have a special debt of gratitude to the Planned Parenthood Action Fund, which spent $830,686 on his behalf. The fund, the political arm of Planned Parenthood, does not reveal its donors. He’ll also owe extra thanks to Moveon.org Political Action, which has spent nearly $263,000 to support his candidacy. Moveon discloses the names of donors who give $200 or more.

If Handel prevails, she’ll start her term beholden to allies of President Trump, though in many cases their precise identities will be at least partially hidden. America First Policies, a nonprofit founded by Trump advisors, has spent $1.3 million to support Handel. Ending Spending, a nonprofit started by TD Ameritrade founder Joe Ricketts, spent $1.3 million on Handel, and the 45 Committee — linked to Ricketts’ son — has spent $371,852 on his behalf. Once prominent Trump antagonists, the Ricketts family has moved into the president’s inner circle since the November election.

The U.S. Chamber of Commerce, the second-highest-spending dark money organization in 2016, has spent more than $1 million to help elect Handel.

All of those groups are non-profits that operate under tax laws that allow them to conceal their donors on campaign finance reports. But there’s no prohibition on donors revealing themselves to the candidate, and whoever wins can expect to see some of those “hidden” benefactors appearing at his or her office door, seeking a tangible expression of gratitude from the new congressman/woman.