Environmentally-minded billionaire Tom Steyer gave another $15 million to his NextGen Climate Action in September, his outside spending group whose $20 million in campaign spending last month made it September’s No. 1 spender. The donation also brings Steyer’s super PAC contributions for the 2014 cycle to an eye-popping $55.9 million.

An analysis of the latest campaign filings using Sunlight’s Real-Time Federal Campaign Finance tracker provides a revealing view of how the spenders we know about are positioned in the final weeks before the election. The past week has given us the opportunity to take a rare comprehensive look at the money landscape: Reports from political committees that file on a quarterly schedule were due Oct. 15, while monthly filers’ latest reports were due at midnight. Sunlight is taking advantage of our Real-Time tool’s analytic capacity to crunch the numbers today, and we’ll be updating this post with new material.

NextGen, which is focused on electing candidates prepared to act aggressively to counter climate change, has made multi-million dollar expenditures supporting Democratic Senate candidates in Colorado, Michigan and Iowa.

In addition, the Steyer group also is funneling money to a variety of allied federal and state groups, including:

• $5 million to NextGen’s state outpost in Florida, where the group is going after incumbent Republican Gov. Rick Scott;
• $925,000 to the League of Conservation Voters’ Victory Fund, $600,000 of which was earmarked for the Michigan Senate contest;
• $500,000 to the group’s state PAC in Maine;
• A $250,000 check to liberal veterans’ group VoteVets.org.

The green super PAC is a campaign behemoth. The $16.9 million NextGen raised in September — including a $1 million check from hedge fund manager Meridee Moore, and six-figure contributions from millionaire heirs Pat Stryker ($500,000) and Sam Walton ($200,000) — was the biggest fundraising haul of any committee filing monthly or quarterly reports to the Federal Election Commission this month. Tellingly, its expenditures trumped those of the Republican National Committee over the same time period.

But individuals on the other side of the ideological divide are ponying up too. This month’s FEC filings unveiled megadonations from conservative super PAC players: Among those splurging on the Freedom Partners Action Network was financial wiz Robert Mercer ($2.5 million) as well as Charles ($2 million) and David ($2 million) Koch; and Karl Rove’s American Crossroads got a $2 million check from Public Storage founder Wayne Hughes, $1.25 million from hedge fund manager and gay rights activists Paul Singer and $1 million from Robert Rowling’s TRT Holdings, which is behind Gold’s Gym and the Omni chain of hotels.

One caveat to all this: As Sunlight has frequently observed in this space, the proliferation of political nonprofits, which are not required to disclose donors, has given rise to considerable “dark money” spending. The dark money spending we know about is now up to $105 million for 2014 — and that’s not all of it. The names of the donors behind those funds are unlikely to surface.

Steyer’s political largesse has drawn comparisons to the Koch brothers spending machine. Politico’s Ken Vogel reported in May that the businessmen planned to raise and spend $125 million in the midterms through the donor network to Americans for Prosperity, but incomplete disclosure of political nonprofits makes it impossible to know what the duo has invested in this election cycle.