NEW YORK >> Facebook elevated concerns about election interference today, announcing that it had uncovered “sophisticated” efforts, possibly linked to Russia, to manipulate U.S. politics and by extension the upcoming midterm elections.

The company was careful to hedge its announcement; it didn’t link the effort directly to Russia or to the midterms, now less than a hundred days away. And its findings were limited to 32 apparently fake accounts on Facebook and Instagram, which the company removed because they were involved in “coordinated” and “inauthentic” political behavior.

But official Washington connected those dots anyway, not least because the reported activity so closely mirrored Russian influence campaigns during the 2016 presidential election. Nearly 300,000 people followed at least one of the newly banned accounts and thousands expressed interest in events they promoted.

“This is an absolute attack on our democracy,” said Virginia Sen. Mark Warner, the top Democrat on the Senate intelligence committee, which Facebook had briefed in advance. Warner expressed “pretty high confidence” that Russia was behind the assault.

A spokesman for Senate Judiciary Chairman Chuck Grassley said Facebook had informed his office that “that a limited group of Russian actors has attempted to spread disinformation using its platform and that the affected groups are affiliated with the political left.”

The identified accounts sought to “promote divisions and set Americans against one another,” wrote Ben Nimmo and Graham Brookie of the Atlantic Council’s Digital Forensic Research Lab in a blog post today. The nonprofit is working with Facebook to find and analyze abuse on its service.

The perpetrators, Facebook noted, have been “more careful to cover their tracks” than in 2016, in part because of steps Facebook has taken to prevent abuse over the past year. For example, they used virtual private networks and internet phone services to mask their locations, and paid third parties to run ads on their behalf.

After it became clear that Russia-linked actors used social media to try to influence the 2016 U.S. election, Facebook has escalated countermeasures intended to prevent a repeat. It has cracked down on fake accounts and tried to slow the spread of fake news and misinformation through outside fact-checkers. The company has also announced new guidelines around political advertisements, requiring disclosure of who paid for them and keeping a database.

Facebook has ramped up spending on these and other measures, so much so that it finally spooked investors with a forecast of lower profitability last Wednesday. Facebook’s shares promptly dropped almost 20 percent and haven’t recovered.

While the company would not say who is behind the efforts, Facebook said it uncovered links between the accounts it just deleted and those created by Russia’s Internet Research Agency in the 2016 influence effort.

For example, the Atlantic Council’s researchers noted “language patterns that indicate non-native English and consistent mistranslation, as well as an overwhelming focus on polarizing issues.” The accounts seemed focused on building up an online audience and moving it to offline events, such as protests.

The earliest page was created in March 2017. Facebook says more than 290,000 accounts followed at least one of the fake pages. The most followed Facebook pages had names such as “Aztlan Warriors,” ”Black Elevation,” ”Mindful Being,” and “Resisters.”

Facebook didn’t provide detailed descriptions of those pages. But their names parallel those of 2016 groups established by Russian agents to manipulate Americans with particular ethnic, cultural or political identities. That effort targeted people with both liberal and conservative leanings.

This time, though, the pages Facebook found focused “exclusively at engaging and influencing the left end of the American political spectrum,” according to the Atlantic Council researchers.

Facebook says the pages ran about 150 ads for $11,000 on Facebook and Instagram, paid for in U.S. and Canadian dollars. The first ad was created in April 2017; the last was created in June 2018.

On today’s conference call, Facebook executives declined to say much more, including whether the pages spanned a range of political opinion and whether the accounts mentioned specific candidates or politicians.

California Rep. Adam Schiff, the top Democrat on the House intelligence committee, said more work needs to be done before the midterm elections.

“Foreign bad actors are using the exact same playbook they used in 2016,” he said. They are “dividing us along political and ideological lines, to the detriment of our cherished democratic system.”

The intelligence panel is planning to hold a hearing in early September with Facebook Chief Operating Officer Sheryl Sandberg, Twitter CEO Jack Dorsey and an executive from Google.

President Donald Trump has offered mixed messages on Russian interference, at times even calling it a “hoax.” After appearing to question whether the Russians would try again to interfere earlier this month, he acknowledged last week in a tweet that the midterms were a likely target. But he said that Democrats, not his fellow Republicans, would be the ones supported by Russia.

Today, White House spokesman Hogan Gidley said that Trump “has made it clear his administration will not tolerate foreign interference in our electoral process from any nation state or other malicious actors.”