Democrats have denounced anonymous money in politics for years, but 2020 brought a tidal wave of it into the election to benefit their party.

More than $320 million of so-called “dark money” helped boost Democrats in the White House and congressional races — more than double the anonymous dollars that aided Republicans in this year’s federal elections, a new analysis shows.

A top beneficiary: President-elect Joe Biden. Nearly $132 million in anonymous money backed his White House bid, compared to nearly $22 million to aid President Donald Trump, according to an analysis by the Center for Responsive Politics.

The analysis by the center defines dark money as donations and spending by nonprofits that do not disclose the sources of the money. It also includes money flowing into politics from limited liability corporations operating as shell companies.

The trend toward Democrats is a stark reversal from previous presidential election cycles in which dark money overwhelmingly boosted Republicans.

The new figures come as candidates, political parties and outside groups, including those funded by nonprofits that conceal their donors — unleash a fresh wave of spending in Georgia to influence two US Senate runoffs that will determine which party controls the chamber. More than $287 million already had been booked on television ad buys in the state through Wednesday, according to a CNN tally of advertising data collected by Kantar’s Campaign Media Analysis Group.A dark money mystery in Florida centers on the campaign of a spoiler candidate who appeared to help a Republican win by 32 votes

Even as the spending frenzy continues, campaign-finance watchdogs are calling on President-elect Joe Biden and lawmakers on Capitol Hill to take aggressive steps curb anonymous spending in elections.

“This is a rotten system, but as long as it exists, both parties are going to use it,” said Fred Wertheimer, who runs the watchdog group Democracy 21 and is part of a coalition of more than 170 groups, urging the incoming president to tackle issues ranging from voting rights to greater transparency in campaign finance.

“The test for us is: What are you prepared to do about the system?” Wertheimer said.

Biden’s aides declined to comment on the record but pointed to his decision to allow reporters to listen in on his campaign fundraising events as one sign of his commitment to transparency.

They also note that the former vice president, a longtime proponent of public financing for federal candidates, has proposed sweeping changes to address the role of money in politics. Those proposals include enacting legislation that would bar dark money nonprofits from spending in elections and establish matching public funds for candidates seeking small-dollar contributions to spur more grassroots giving.

The outcome of the Georgia Senate races could determine whether any of those proposals make headway in Congress

Big players

The analysis examined dark money donations to super PACs, along with any money that nonprofits spent directly on so-called independent expenditures that call for the election or defeat of specific candidates.

One Nation, an anonymously funded nonprofit associated with the political operation of Senate Majority Leader Mitch McConnell, R-Kentucky, is the largest anonymous donor in federal races to date, the analysis shows. It sent nearly $63 million to its aligned super PAC Senate Leadership Fund.https://649f4cd954cd6a925120189218d24980.safeframe.googlesyndication.com/safeframe/1-0-37/html/container.html?n=0

The anonymous money from One Nation accounted for 20% of the Senate Leadership Fund’s total haul.View this interactive content on CNN.com

So far, The Senate Leadership Fund has spent more than $246 million in Senate contests in this cycle to help McConnell and Republicans to retain their hold on the Senate. And as of Wednesday, it had plowed more than $43 million into advertising in the Georgia Senate runoffs, Kantar’s data show.

The fund and its other political arms recently announced plans to spend about $70 million on TV and radio ads to sway the Georgia contests.

Three liberal groups, led by a little-known organization called the Sixteen Thirty Fund, account for a third of the dark money donations that have benefited Democrats, the analysis shows.

The center’s tally shows $52 million flowing from the Sixteen Thirty Fund to other groups active in the 2020 elections.

In recent years, the Sixteen Thirty Fund has emerged as a hub for groups on the left, providing administrative, legal and accounting services for liberal projects. Groups operating as arms of the Fund include Demand Justice, which has opposed President Donald Trump’s judicial nominees.

It also helped Democratic donors send money to other dark money groups that popped up during the 2020 election cycle to target vulnerable Republican senators. For instance, nearly $4 million went to a nonprofit dubbed, Maine Momentum, that pummeled Republican Sen. Susan Collins with early attack ads. In the end, Collins prevailed over her Democratic challenger Sara Gideon.

The Fund also directed $300,000 to the Lincoln Project, a super PAC run by former GOP operatives that produced lacerating anti-Trump ads.

In all, the Sixteen Thirty Fund took in more than $137 million from anonymous donors in 2019, according to its most recent tax return, first reported by Politico. That included a $33 million contribution from a single unnamed donor.

Federal rules require nonprofits to publicly detail the amount of each donation they receive, but they don’t have to provides the names or any identifying information about those donors.

Over the last two years, many donors “felt compelled to give as never before to support our democracy and advance progressive goals, including some who previously supported Republicans or were not engaged in politics,” Amy Kurtz, the fund’s executive director, said in a statement.

But “given the divisive nature of politics today, some of these donors chose to remain anonymous,” she added.

Kurtz said the group wants to overhaul the current campaign finance laws but will play by the rules in effect now.

Officials with Priorities USA Action, the main super PAC that supported Biden’s campaign, echoed that. The super PAC relied on anonymous contributions through its nonprofit arm, Priorities USA. Those dollars accounted for a little more than $1 out of every $5 the super PAC raised through mid-October, the analysis shows.

“We weren’t going to unilaterally disarm against Donald Trump and right-wing conservatives,” Priorities chairman Guy Cecil said, “but look forward to the day when unlimited money and super PACs are a thing of the past, even if it means putting our own PAC out of business.”

Senate obstacles

A measure pushed by Democrats on Capitol Hill would bring sweeping changes to elections, including requiring nonprofit dark money groups that engage in politics to disclose their larger donors. It would also give federal candidates as much as a 6-to-1 match of public funds for small donations.

The Democrat-led House passed their plan, a bill dubbed H.R. 1, last year. But it has gained no traction in the Republican-controlled Senate. McConnell has made no secret of his disdain for the Democratic efforts to overhaul the campaign finance system.

The Kentucky Republican has called H.R. 1 an “one big, expensive partisan power grab.” And he has steadfastly opposed any attempts to unmask donors to dark money nonprofits, warning that “angry left-wing activists” are poised “to harass and bully anyone who’s contributing to national conversations with political views that they disagree with.”

The Georgia runoffs on January 5 will determine whether McConnell retains his hold on the Senate and likely the fate of campaign finance laws. Republicans currently hold 53 seats but lost one in Arizona and one in Colorado and picked up one in Alabama.

If Democrats Raphael Warnock and Jon Ossoff topple Republican Sens. Kelly Loeffler and David Perdue in Georgia, Vice President-elect Kamala Harris will break tie votes in the Senate.

No matter the Georgia outcome, some activists hope Biden will be at the vanguard of change — given his long record in the Senate supporting public financing of elections. (Biden first co-sponsored legislation establishing public financing for congressional candidates in the 1970s.)

As president, Biden could take action on his own, such as requiring companies with federal contracts to disclose their political spending, said Lisa Gilbert of the left-leaning watchdog group Public Citizen. “We have sky-high expectations that we believe he will meet,” she said of Biden.

Meredith McGehee, who is executive director of Issue One and works with Democrats and Republicans on campaign finance transparency, credits Biden for his early Senate support for public financing of elections. But she says: “How this administration will approach dark money is very much an open question.”

She has noticed a trend on Capitol Hill, however: As Democrats become more adept at deploying anonymous money, Republican senators have grown more concerned about it.

“While Mitch McConnell may continue to call the shots on these issues, at the individual, member-level, they are not big fans of the dark money,” McGehee said. “Republicans have new incentives to want to address dark money because it’s no longer benefiting them solely.”David Wright and Center for Responsive Politics staffers Karl Evers-Hillstrom, Anna Massoglia and Andrew Mayersohn contributed to this report.