(CNN) For all the complaints from Democrats about the amount of big money in politics, Hillary Clinton and Bernie Sanders have raised a staggering amount of cash.

Clinton's campaign raised $112 million in 2015, and top Democratic billionaire donor George Soros recently gave $6 million to her super PAC, according to new figures filed with the Federal Election Commission Sunday night. Sanders, for his part, raised roughly $73 million last year, but as his insurgent candidacy gains momentum, he continues to bring in cash. The Vermont senator raised more than $20 million in January, his campaign said Sunday.

On the Republican side, front-runner Donald Trump has lent his campaign more than $12 million through the end of 2015. Yet while he consistently states he is not raising money, his campaign recorded donations worth over $2 million in the fourth quarter, according to the filing. Trump boasted at the end of the year he would begin spending $2 million per week -- that spending is not included in Sunday's report.

Trump can easily self-fund his campaign, but GOP contenders Marco Rubio and Ted Cruz still must hit the donor circuit. Rubio did well in the fourth quarter, raising $14 million — twice that of his Florida rival, Jeb Bush. His super PAC also won major donations from conservative hedge fund billionaires Paul Singer and Ken Griffin. And Cruz ended the year in a strong position. He raised $20.5 million in the last three months of 2015, ending with $18.7 million.

All campaigns and super PACs are required to file their 2015 reports with the FEC by the end of Sunday. Strong numbers, especially their cash-on-hand heading into the month, will instill donor confidence in their campaign's ability to go the distance, even if they don't finish atop the Iowa caucuses or New Hampshire primary. Sunday is also the first chance in six months to see what how much big donors like Soros are giving to super PACs, the outside groups that can raise and spend unlimited amounts of cash to help candidates.

Sheldon Adelson, the Las Vegas-based casino magnate who is expected to give millions of dollars to help the GOP nominee this year, is one of those big donors. He did cut a check last year, but it wasn't for $1 million. It was $2,700 for Cruz. That's the maximum allowed for a personal donation to a campaign; major Adelson spending will come via a super PAC or not-for-profit group.

Clinton's fundraising prowess

The former secretary of state brought in over $37 million in the final three months of 2015 and started the year with $38 million in the bank. At the same time, the campaign spent $35 million in those three months. She continues to benefit from millions of dollars raised by her super PACs, including Priorities USA, which said Friday it has raised $50 million through this month. Two other groups supporting Clinton, American Bridge and Correct the Record, brought in an additional $6 million total.

And while Sanders has sworn off super PACs and criticizes Clinton's largesse, a group run by National Nurses United is backing the Vermont senator regardless and has raised $2.3 million, with about half of that remaining, the group reported.

Clinton's haul also meant a windfall for the Democratic National Committee and state Democratic parties across the country, who worked with Clinton's campaign to raise money for the Hillary Victory Fund. In total, Clinton's campaign raised $18 million for the DNC and state parties.

"We're heading into the first caucuses and primaries with an organization second to none thanks to the support of hundreds of thousands of people across the country," said Robby Mook, Clinton's campaign manager. "We will have the resources necessary to wage a successful campaign in the early states and beyond."

Sanders campaign manager Jeff Weaver touted the number of individual contributions -- 3.25 million — the campaign has received. "As Secretary Clinton holds high-dollar fundraisers with the nation's financial elite, our supporters have stepped up in a way that allows Bernie to spend the critical days before the caucuses talking to Iowans about his plans to fix a rigged economy and end a corrupt system of campaign finance," Weaver said in a statement.

O'Malley in debt

Martin O'Malley, the third Democrat in the race, is in serious trouble. He ended the year with $170,000 in the bank. Worse, his campaign is $530,000 in debt.

O'Malley entered the fourth quarter with just over $800,000 and raised $1.5 million -- including a $500,000 loan. But it spent over $2.1 million, with no upward change in the polls.

Marco Rubio outraises Jeb Bush, bags two billionaires

Jeb Bush's campaign struggled to raise money in the fourth quarter as the former Florida governor fell in the polls.

His operation raised $7.12 million in the last three months of 2015, half that of his former protege and now rival from Florida, Marco Rubio. The senator's campaign raised just over $14 million in the fourth quarter, ending the year with $10.39 million, it said Sunday night. Bush's campaign had less than $8 million cash on hand.

Meanwhile, Bush's super PAC, Right to Rise, had an expensive summer and fall. The group has spent roughly $60 million backing Bush, as well as airing ads attacking GOP rivals like Marco Rubio. Bush's poll ratings, however, have not been helped by the big spending. A CNN/ORC poll released July 1 had Bush leading the Republican field at 19% nationally. Last week, he was at 5%.

The group does still have plenty of money — over $58 million. But as Bush fell in the polls, it raised only $15 million in the final six months of 2015, $10 million coming from former AIG chief executive Hank Greenberg.

As for Rubio, his Conservative Solutions PAC raised nearly $16 million in the second half of 2015 and had about $14 million on hand.

Rubio in recent months has successfully courted some of the GOP's leading financiers, and it is showing.

Several individuals gave $1 million to the group, including Norman Braman, a Rubio mentor from Florida who has now given a total of $6 million to the super PAC. Singer and Griffin, meanwhile, each gave $2.5 million.

Ben Carson burns cash

Ben Carson, meanwhile, also had a poor fall in the polls. At one point in the lead, Carson has consistently dropped. His campaign was also hit by the departure of his campaign manager.

But his campaign spent big. He raised $22.7 million in the fourth quarter, spending over $27 million. He ended the year with only $6.6 million on hand, according to FEC records.

Carson's main super PAC, The 2016 Committee, raised $6.1 million in the second half of 2016, but spent nearly all its money and retained only $560,000 as of December 31.

Republican super PACs

Rand Paul's authorized group, America's Liberty PAC, has been beset by scandal -- its top two operatives were once indicted -- and now has poor fundraising results: it only collected $1.4 million, with only about $830,000 on hand.

Other groups are in a stronger position: John Kasich's two super PACs, brought in over $3.6 million -- much of which through smaller, five-digit checks -- and had under $2 million remaining. Christie's group, America Leads, raised $5.1 million thanks to prominent hedge-funder Steve Cohen, who sank another $2 million to the super PAC. It still had $3.3 million on hand.

Stand for Truth, a mysterious pro-Cruz super PAC that formed only recently, revealed its donors on Sunday -- nearly half of the money raised by it came from the family of Adam Ross, a close Cruz friend from Texas. It still had $2.1 million in the bank.