Fredreka Schouten

USA TODAY

Republican presidential nominee Donald Trump has relied heavily on lots of passionate small-dollar donors — and some $56 million of own money — to fuel his campaign.

But new campaign-finance filings offer a snapshot of some of the super-wealthy individuals who have decided to write big checks to pro-Trump super PACs in the campaign's homestretch.

Casino magnate Sheldon Adelson and his wife Miriam, are among the biggest pro-Trump donors to emerge in the final weeks of the campaign. The billionaire and his physician wife contributed a combined $10 million last month to Future45, a newly active super PAC that is running ads that slam Trump's Democratic rival Hillary Clinton.

The Adelsons, the largest super PAC donors of the 2012 presidential contest, have just started donating big sums to the 2016 election and already have contributed a combined $40 million to super PACs working to preserve Republican control of the House and Senate, vaulting them to the top of this election's list of mega-donors.

SuperPACs can raise unlimited sums but are barred from coordinating their advertising decisions with the candidates they support.

Future45 is one arm of a conservative political operation organized and partially funded by TD Ameritrade founder J. Joe Ricketts and his son, Todd Ricketts. Joe Ricketts, whose family owns the Chicago Cubs, donated $1 million to the group last month, reports filed over the weekend with the Federal Election Commission show.

Linda McMahon, who co-founded a wrestling franchise and ran unsuccessfully for the U.S. Senate, also has emerged as a big Trump donor, contributing $6 million in August and September to Rebuilding America Now, another pro-Trump super PAC. The group is chaired by Florida's Republican Gov. Rick Scott.

Home Depot co-founder Bernard Marcus also donated to Rebuilding America Now in the July-to-September fundraising quarter, contributing $5 million. Arkansas poultry magnate Ronnie Cameron donated $2 million.

Wealthy donors had been slow to rally around the Republican nominee in the early stages of the campaign, putting pro-Trump super PACs at a financial disadvantage.

Together, Future45 and Rebuilding America have raised a combined $23.8 million so far in the election cycle. By comparison, the pro-Clinton super PAC, Priorities USA Action, had raised $133 million through the end of August; it will file a September fundraising report later this week.

Team Trump raises $100 million