The Democratic Senatorial Campaign Committee raised $6.8 million last month, setting a new record for February fundraising and outraising its Republican counterpart by more than $1 million.

The National Republican Senatorial Committee raised $5.47 million in February, and ended the month with $12.75 million cash on hand and no debt.

According to a committee aide, the DSCC had $18.1 million cash on hand, up from $15 million at the end of January. The committee is continuing to pay down its debt at a steady pace, with just $1.2 million in debt at the end of February, down from $2.5 million the month before.

The DSCC has raised $66 million overall, the largest fundraising haul the committee has ever posted at this point in an election cycle.

The Democratic committee has consistently outraised the NRSC this cycle, and at the end of February raised over $19 million more than its GOP counterpart overall.

Still, Democrats are facing an increasingly uphill battle in defending their six-seat majority. They've been grappling in recent weeks with a tough political climate and an expanding map, with top Republican recruits jumping into the Colorado Senate race and taking steps toward the New Hampshire Senate race.

The DSCC has already pledged $60 million toward an expansive turnout effort spanning 10 battleground Senate states, and with two new competitive races on the map, that investment may need to grow.

NRSC communications director Brad Dayspring suggested in a statement that the expanding map would in fact cause Democrats to abandon candidates in tough states, like West Virginia, Montana and Kentucky.

"From Alaska to Louisiana, New Hampshire to Oregon, it's clear that Republicans have expanded the map and a strong field of candidates to win the Senate majority. Democrats are on defense in fourteen states, so it's simply a matter of time before they have to start diverting resources from a Mary LandrieuMary LandrieuYou want to recall John McCain? Good luck, it will be impossible CNN producer on new O'Keefe video: Voters are 'stupid,' Trump is 'crazy' CNN's Van Jones: O'Keefe Russia 'nothingburger' video 'a hoax' MORE or a Kay HaganKay HaganLinking repatriation to job creation Former Sen. Kay Hagan in ICU after being rushed to hospital GOP senator floats retiring over gridlock MORE to Mark UdallMark UdallDemocratic primary could upend bid for Colorado seat Picking 2018 candidates pits McConnell vs. GOP groups Gorsuch's critics, running out of arguments, falsely scream 'sexist' MORE or Jeanne ShaheenCynthia (Jeanne) Jeanne ShaheenHomeland Security searching some social media doesn't violate privacy The feds shouldn't blackball Kaspersky without public evidence Week ahead: Crunch time for defense bill’s cyber reforms | Equifax under scrutiny MORE.  

"Meanwhile, it's clear that long shot candidates like Natalie Tennant, John Walsh and Alison Lundergan Grimes will have to be cut off," he said.

In a statement, DSCC executive director Guy Cecil tied Republicans to the Koch brothers while touting Democratic grassroots support.

“Across the country Republican Senate candidates are embracing a dangerous agenda that’s good for billionaires like the Koch Brothers and bad for nearly everyone else in the country. Their allegiance to the Kochs means countless millions to benefit their campaigns, while Democrats are boosted almost entirely by our grassroots donors and thousands of generous people across the country who care about having a Senate that works for the middle class,” he said.

The billionaire brothers have become a frequent target of Democratic attacks after a GOP group that counts them as primary benefactors poured $30 million into competitive races on ObamaCare attacks, which polling has shown is taking a toll on some candidates.

Cecil did warn, however, that there’s no room for the Democratic fundraising pace to slow.

“We know our biggest challenge in the midterms is turnout, and we need our supporters to continue to help us win each month so we can provide our campaigns with cover on television and fund the most aggressive field effort in history,” he said.

—This piece was updated at 9:11 a.m. to reflect the NRSC's numbers.