Candidates locked in the nine tightest Senate races in the country raised over $57 million in the third fundraising quarter.

Several of these races remain too close to call, and these funds will be used to boost the candidates out of the margin of error and into the lead in the final three weeks of their campaigns.

Elizabeth WarrenElizabeth WarrenJuan Williams: McConnell won big by blocking Obama This week: Government funding deadline looms Week ahead: Cures bill nears finish line MORE, Democrat for Senate in Massachusetts, announced raising the largest haul — and outraised her opponent by the largest amount — of them all, and perhaps the largest of any Senate candidate nationwide. She raised $12.1 million in the third quarter, bringing her year-to-date fundraising total to $36.3 million — over $8 million more than GOP opponent Sen. Scott Brown.

Brown's campaign said he brought in a considerable sum as well, but at $7.54 million, his fundraising total for the third quarter fell far short of Warren's. He's raised nearly $27.5 million for the year.

Democratic Rep. Joe DonnellyJoe DonnellyTrump’s vow on Medicare in doubt after HHS choice Red-state Dems face tough votes on Trump picks Red-state Democrat: I'll oppose Trump's health chief MORE, running for Senate in Indiana, faces a disadvantage similar to Brown's. Opponent Richard Mourdock raised twice as much as him in the third quarter, bringing in a $3 million haul.

Democrats in three other toss-up races bested their Republican opponents in fundraising for the third quarter. Rep. Tammy BaldwinTammy BaldwinThis week: Pelosi's test Dems question FCC on data-free apps 115th Congress will be most racially diverse in history MORE brought in $1 million more than her opponent Tommy Thompson, posting a $4.6 million haul in the third quarter to Thompson's $3.6 million.

In Virginia, Democrat Tim KaineTim KaineTrump adviser: Sanders would have made for tougher race as Clinton's VP Trump adviser: Clinton/Sanders ticket would've been tougher to beat Terry McAuliffe: Clinton likely done with politics MORE outraised Republican George Allen by a little less than $1 million. He posted $4.4 million in receipts for the third quarter, compared to Allen's $3.5 million.

And in Arizona, Richard Carmona outraised opponent Rep. Jeff FlakeJeff FlakeSenators crafting bill to limit deportations under Trump Interest groups keep the political ads coming Overnight Healthcare: Cures bill sails through House | Walden frontrunner for Energy and Commerce gavel MORE for the second quarter in a row, this time by about $500,000. He brought in $2.2 million in the third quarter, while Flake brought in $1.7 million.

Most candidates, like Flake and Carmona, saw a disparity of only a few hundred thousand dollars in their third-quarter fundraising hauls.

Closest among the nine toss-up races was Montana, where Republican Rep. Denny Rehberg outraised Sen. Jon TesterJon TesterRed-state Dems face tough votes on Trump picks Montana Republican warns of Senate challenge to Tester Vulnerable Dems ready to work with Trump MORE by only about $100,000, with $2.4 million to Tester's $2.3 million. That reflects the razor-thin polling edge on which the race currently stands: The RealClearPolitics average of polls gives Rehberg a .3-point advantage over the incumbent.

Incumbent Dean HellerDean HellerGovernments and businesses: Teaming up for taxpayers GOP senator won't rule out 2018 run for Nevada governor A holiday surprise: Will Congress protect privacy? MORE (R) outraised his challenger, Rep. Shelley Berkley (D), by a similarly small margin, bringing in $1.9 million to her $1.6 million.

And in North Dakota, it remains unclear how much separates Democrat Heidi HeitkampHeidi HeitkampFeds deny permit for Dakota Access pipeline Priebus says State announcement coming in next 2 weeks Trump flirts with Dems for Cabinet MORE from Rep. Rick Berg, as Heitkamp's campaign only revealed that the candidate raised $1.6 million in the third quarter, while Berg's campaign said he raised $1.57 million. Heitkamp's rounding of her total could obscure how close the numbers really are.

The candidates can't all use every dollar they reported raising from July 1 to Sept. 30. Donors can apportion funds for use in the primary or general elections, and candidates in Arizona, Connecticut, Wisconsin and Massachusetts all faced primaries during that period. Though they reported raising millions, in most cases, hundreds of thousands of the sum reported may have only been accessible for the first month or so of the quarter, the period in advance of their state's primary.

Every candidate but one in these toss-up races, Republican Linda McMahon, running in Connecticut, has reported total receipts for the third quarter. McMahon raised a record-breaking $20 million haul in the third quarter during her 2010 run, in part because of an influx of funds she contributed to her own campaign. Her opponent, Rep. Chris MurphyChris MurphyWrestling mogul McMahon could slam her way into Trump administration Dem on Trump's foreign policy moves: 'That's how wars start' House passes medical cures bill MORE, announced raising $3 million in the third quarter.