Florida Democrats picked up some major fundraising momentum in August and September, with candidates out-raising their Republican opponents in seven key Congressional races during that time.

Democrats raised more money than Republicans in the races for Florida's 6th, 15th, 16th, 18th, 25th, 26th and 27th — all potential Democratic flips, according to FEC filings. Of the Democrats running in those seven districts, five led their Republican opponents in total cash on hand going into the final stretch of the 2018 elections. (The analysis in this article includes figures from the campaigns' official committees, not outside or PAC money.)

Read more: The Buzz's Florida congressional vulnerability rankings, post-primary edition

Included in that list is Republican gubernatorial candidate Ron DeSantis' old district, FL-6, where Democrat Nancy Soderberg raised almost $800,000. Soderberg's Republican opponent, Michael Waltz, raised just over $600,000. The election forecasting website Fivethirtyeight lists the district as "lean Republican," giving Soderberg about a 27 percent chance to flip it.

Democrat Kristen Carlson, who's running a strong race for the FL-15 left open by Republican Dennis Ross' retirement, also dominated her Republican opponent in third quarter fundraising. She raised over $600,000, compared to Republican Ross Spano's $219,000 haul. Fivethirtyeight says that district, which favored President Trump by 10 points in 2016, is a dead heat.

In FL-27, another seat left open by a retiring Republican, Democrats are desperately hoping to win a district that favored Hillary Clinton by almost 20 points. Donna Shalala raised over $866,000 in the third quarter, compared to Republican Maria Elvira Salazar's haul of $520,000.

Those are races for open seats. In a district like FL-16, where a Democrat has to knock off a Republican incumbent, the climb is steeper. But Democrat David Shapiro still out-raised incumbent Republican Vern Buchanan in the third quarter by over $360,000. Fivethirtyeight says Shapiro has about a one-in-seven chance to flip the seat.

Read more: We interviewed the candidate who's trying to flip FL-16

It was a similar story in FL-18 and FL-25, where Democrats Lauren Baer and Mary Barzee out-raised incumbent Republicans Brian Mast and Mario Diaz-Balart. Barzee has about a 25 percent chance to win her race, per Fivethirtyeight; the forecasting site gives Baer the longest odds of any Democratic candidate mentioned in this article.

Republicans have some reason for optimism as well. For one thing, Fivethirtyeight says Republicans are favored to keep five of the seven districts mentioned here. For another, fundraising is only so important at this late stage. Many television ad buys have already been made, and the closer a buy is made to election day, the more expensive it is.

Also on the fundraising front, Republican mega-donor and billionaire casino magnate Sheldon Adelson has pledged to donate tens of millions more to the Republican effort to maintain control of Congress before all is said and done.

Democrats need a net of 23 House seat pickups to regain control of the chamber in 2019. Fivethirtyeight gives the party a five-in-six chance to gain at least that many. If Democrats do, Florida could be a big reason why.