The U.S. political committee accuses the tech giant of "discriminating" against it by "throttling its email messages because of the RNC’s political affiliation and views," according to a lawsuit filed in U.S. District Court in California.

"Google has relegated millions of RNC emails en masse to potential donors’ and supporters’ spam folders during pivotal points in election fundraising and community building," the RNC said in the lawsuit.

Google rejected the claims.

"As we have repeatedly said, we simply don't filter emails based on political affiliation. Gmail’s spam filters reflect users’ actions," Google spokesperson José Castañeda said in a statement. "We provide training and guidelines to campaigns, we recently launched an FEC-approved pilot for political senders, and we continue to work to maximize email deliverability while minimizing unwanted spam," he said, referring to the Federal Election Commission.

Spam filters on email services typically weed out unsolicited "spam" messages and divert them to a separate folder.

The RNC said that for most of the month, nearly all of its emails end up in users’ inboxes but at the end of the month, which is an important time for fund-raising, nearly all of their emails end up in spam folders.

"Critically, and suspiciously, this end of the month period is historically when the RNC’s fundraising is most successful," the lawsuit said, adding that it does not matter whether the email is about donating, voting or community outreach.

The committee said the "discrimination" had been going on for about 10 months despite its best efforts to work with Google.

It said the alleged routing of its emails to spam folders had eaten up revenue and that more money would be lost in coming weeks as midterm elections loom.

Republicans have long accused big tech companies of discriminating against conservative views and suppressing free speech, an assertion tech companies strongly deny.