ActBlue, a nonprofit whose online fundraising tools have been used to varying degrees by nearly every Democrat running for Congress, says it has raised more than $2.9 billion for Democrats and progressive organizations since its founding in 2004. September was the biggest month in its history.

An analysis of campaign finance data by the Center for Public Integrity and FiveThirtyEight shows that ActBlue is handling more political contributions than ever before. Between January 2017 and Sept. 30, 2018 — the most recent date for which Federal Election Commission data is available — nearly $564 million, or about 55 percent of all contributions from individual donors to Democratic congressional candidates, passed through the platform, compared to about 19 percent at this point in the 2014 election.