"In a city struggling with homelessness, Amazon is dropping an outrageous amount of money to defeat progressive candidates fighting for working people," Sanders, an independent from Vermont, wrote on Twitter. "The way Amazon conducts itself in its hometown is a perfect example of the out-of-control corporate greed we are going to end."
Warren, a Democrat from Massachusetts, had a similar take.
"Surprise: Amazon is trying to tilt the Seattle City Council elections in their favor. I'm with the Seattle council members and activists who continue standing up to Amazon." Warren wrote on Twitter. "Corporations aren't people, and I have a plan to get big money out of politics."
The homegrown Seattle company confirmed to FOX Business that it dropped a cool $1.05 million on the election in October, bringing its total contributions this year to $1.45 million.
Amazon said its contributions can help the city solve problems like homelessness.
"We are contributing to this election because we care deeply about the future of Seattle," Amazon spokesperson Aaron Toso told FOX Business in October. "We believe it is critical that our hometown has a city council that is focused on pragmatic solutions to our shared challenges in transportation, homelessness, climate change and public safety."
Amazon's spending comes after the City Council approved, then repealed, a measure requiring companies with annual revenues of $20 million or more to contribute $275 per employee annually. At the time, the council said the so-called head tax would raise about $50 million per year toward the development of affordable housing, homeless shelters and other outreach efforts.
Amazon's contributions are being distributed through the Civic Alliance for a Sound Economy, a Seattle-based political action committee that represents businesses in the area. While there are limitations on how much contributors can give to individual candidates, there are no limits on donations to PACs that spend separately from specific campaigns.
According to its website, CASE's primary issues are traffic and congestion, homelessness and wage and business growth. CASE is linked to the Seattle Chamber of Commerce.
Meanwhile, some candidates are capitalizing on their opposition to Amazon.
"What's at stake this year is who runs Seattle — Amazon and big business or working people," Councilwoman Kshama Sawant, a Socialist, wrote on her website.
"This year, corporate PACs are unleashing a record-breaking corporate onslaught against Councilmember Kshama Sawant. Wealthy Republicans, notorious real-estate developers, and dozens of top Amazon executives are bankrolling her opponent," Sawant wrote on her site, referencing her opponent Egan Orion.
However, conservative radio host Jason Rantz pointed out that campaign filings show that Sawant's team bought a printer, tables and other items from Amazon early in the campaign.
FOX Business' inquiries to Sawant's campaign, Orion's campaign and Amazon were not returned at the time of publication.
FOX News Dan Springer contributed to this report.