(CNN) - As 2020 presidential candidates spend tens of millions of dollars on Facebook and Google ads, one senator is calling on the companies to restrict some of the powerful ways political campaigns can target American voters.
"I think it's time for Facebook and Google to voluntarily suspend micro-targeting of political and issue ads," Sen. Ron Wyden, an Oregon Democrat who's a member of the Senate Intelligence Committee, told CNN.
The senator's concerns come at a time when some political campaigns are spending hundreds of thousands of dollars a week on online ads. Ad buyers can target voters based on their interests and where they live and can even upload lists of voters to target.
Wyden wants Facebook and Google to prevent political campaigns from uploading lists of specific voters.
"I'd rather have them do it voluntarily than requiring a law," he said.
Facebook had no comment. A Google spokesperson pointed CNN to a blog post the company published last year about new policies the company had put in place around political advertising.
Wyden said he was particularly concerned that such "micro-targeting" could be used to dissuade minority groups from voting.
Both companies have said voter suppression campaigns and targeting groups based on their race or ethnicity is not allowed, and have put in new rules around political ads since 2016, but Wyden argues they haven't gone far enough.
Alex Stamos, Facebook's former security chief and now director of the Stanford Internet Observatory, is also calling for some restrictions to be put in place.
"With or without foreign interference, our democracy is moving in a dangerous path where billionaires on both sides are investing in huge data operations, in manipulating individuals across the country through online ads," Stamos told CNN.
Stamos said that while campaigns have been able to target specific voters through direct mail campaigns in the past, online targeting makes such efforts far cheaper.
A campaign that could afford to send one piece of direct mail to a small portion of the country now can afford to show multiple targeted digital ads to every voter in the United States, Stamos said.
The former Facebook executive said Facebook and Google had already taken some positive steps, including efforts to verify that political ad buyers are based in the US. But he added that there are many other online advertising companies that have taken no steps to prevent abuse.
In 2016, a Russian group bought political ads in the lead-up to the presidential election.
"Russians could run a pretty robust campaign just by avoiding Google and Facebook and just using the other services out there," he said.
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