With control of the Senate in doubt and Republicans likely to hold on to their majority in the House, liberal power brokers are ramping up their electoral giving. Left-leaning billionaires continue to top the list of the biggest super PAC donors, with an ever-increasing chunk of the cash coming from just one man, reports to the Federal Election Commission filed in August show.

All in all, outside spending on both sides is driven by donations from a handful of extremely wealthy political activists. Just 34 people nationwide have given one million or more to a super PAC in the 2014 cycle. You can see our list of largest super PAC donors below, populated by data from Real-Time FEC.

We don’t have every contribution made in August to a super PAC — some file on a quarterly schedule. But from what we do know, its unlikely that anyone has outpaced super-giver Tom Steyer, the billionaire former hedge fund manager who’s pouring millions into his own super PACs. After another $15 million donation in August, Steyer alone has accounted for over $40 million in super PAC dough — almost all of which has gone to environmentally-focused NextGen Action that Steyer formed in 2013. Former NYC mayor and media mogul Michael Bloomberg, Democratic donor Fred Eychaner and Illinois conservative Richard Uihlein round out the top five individual donors thus far.

Update: This table has been updated to include John Jordan of California.

Steyer’s money has been largely spent on attack ads against Senate Republican candidates, mostly in Colorado and Michigan, where its attempting to tie challengers Cory Gardner and Terri Lynn Land to the environmentalist’s right wing foils, Charles and David Koch, who spend millions supporting conservative causes. The latest cash infusion shoots the former hedge fund manager’s green super PAC to the top of the heap in terms of dollars raised, outpacing both parties’ national committees and their congressional campaign committees for the month of August.

The top 20 committees by total raised are below:

Senate Majority PAC, a committee with a few fewer degrees of separation from the Democratic party structure, also had a banner month thanks to million dollar donations from NewsWeb chair Fred Eychaner, a Chicagoan and longtime Democratic donor, and Working for Working Americans, funded by the United Brotherhood of Carpenters. That’s on top of a $900,000 contribution from Elizabeth Simons, $750,000 from the American Federation of Teachers and $500,000 courtesy of the operating engineers union.

Meanwhile, conservative donors haven’t been sitting idly by.

With a hardline fiscal conservative stance and a willingness to buck the GOP establishment, Ending Spending Action Fund spent around $1.4 million attacking Republican primary candidates in Georgia and North Carolina. Phil Gingrey, the PAC’s target primary would lose his primary bid, while incumbent Rep. Walter Jones survived an intraparty challenge.

Now that primary season has ended the PAC, controlled and funded by the family of TD Ameritrade founder Joe Ricketts, is kicking in to high gear. It raised $2.3 million in August and just dropped nearly $500,000 on advertising against Gary Peters, the Democratic House member running for the Michigan Senate seat that opened when longtime incumbent Carl Levin chose to seek reelection.

The Ricketts are also major players on the state scene. The family has combined for around $205,200 in contributions to state and local candidates and ballot initiatives this year (around $70,000 of that sum, from Laura Ricketts, supported liberal causes — she even co-hosted a Ready for Hillary). Campaign finance reports from that state show Todd Ricketts, son of Joe, gave $50,000 to the Liberty Principles PAC, ran another Illinoisan on our top givers list, Richard Uihlein, who had contributed $100,000 to Ending Spending Action a week prior.

This data comes from ElectionMoney.org, a real time Illinois campaign finance site that Sunlight helped create along with DataMade and the Illinois Campaign for Political Reform with generous support from the McCormick Foundation.