That Facebook group you joined years ago? It might now be supporting Brett Kavanaugh - or his accuser.

WASHINGTON - To the naked eye, thousands of users on Facebook are backing Supreme Court nominee Brett Kavanaugh.

But some of the groups that seem to advocate for his Senate confirmation - and others that defend Christine Blasey Ford, who recently accused Kavanaugh of sexually assaulting her in the 1980s - amassed their followers months or years before Washington's most politically charged controversy unfolded, according to Facebook's records.

It's yet another sign that public outcry on social media isn't exactly what it appears to be.

One Facebook group - "Justice for Justice Kavanaugh!!!" - has more than 4,200 members, and its description says that Ford's testimony to Congress in September had been "clearly fabricated." But the group came into existence more than four years before that Senate hearing, Facebook's data show. It previously acquired some of its members while acting a group that sought to defend Bill Cosby against sexual assault charges, and later, as a group that touted Trump's proposed "space force."

The largest group purporting to support Ford, "We Believe Christine Blasey Ford (official)," boasts nearly 1,800 members. Before users there warred with each other over the Supreme Court, however, the group had posts about football under the banner "AllSports 247," Facebook records show. At other points, its focus was the March for Our Lives and the dating app Tinder.

The Ford support group changed themes "to spark debate. Not encouraging fighting," said Ryan McGuire, one of the people who oversees it.

The fluid nature of these groups illustrates how the social networking giant's powerful tools for political and community organizing remain major risks for spreading misinformation and stoking unrest, especially as Facebook wages its war against inauthentic activity online and the 2018 election is just weeks away. Groups are at the heart of Facebook chief executive Mark Zuckerberg's stated mission to ensure "online communities strengthen physical communities," as he put it during a speech in 2017. But group owners can easily rename and refocus their groups, while keeping their original members - and their ability to push content into their daily feeds.

Facebook said in the last month it began displaying the two-year history of all groups' name changes to improve transparency. The change offers "more information and insights about a Group, as well as increased accountability for Group admins," said spokesman Andy Stone. With the Ford group, in particular, Facebook said late Thursday it is investigating its recent, whiplash revisions.

Lawmakers see lingering vulnerabilities that malicious actors, including foreign governments such as Russia, can use to their advantage.

"This is one tactic we saw the Russians use in 2016 - using popular, often apolitical content, to build a following for a page, and then later injecting political content to followers ahead of the election," said Sen. Mark Warner of Virginia the top Democrat on the Senate Intelligence Committee.

Warner praised Facebook for allowing users to see more information about the groups they've joined. "But the Russian playbook is out in the open now," he added in a statement. "We can expect to see more of this, and the best way to address it will be through increased transparency."

With groups, Facebook users can create hubs around common interests, whether it's politicians or sports teams. These groups can attract members numbering into the millions, who can elect to be alerted to posts, photos and other updates as they're published online. But there's nothing stopping the administrators of these groups from re-imagining them entirely, switching topics even without the knowledge of supporters.

Users, of course, can exit a group whenever they like. But members may not be immediately aware whenever their communities radically change focus, whether it's to Kavanaugh or another issue entirely. And it could create the illusion that more people support a cause than they do.

One of the largest groups calling for Kavanaugh's confirmation - "Confirm Judge Kavanaugh (Enough is enough)" - had been focused in the past on boycotting Nike and driving GOP turnout to the polls, its name history reflects. It now has more than 27,000 members, about 3,500 of whom joined over the past month. The group's description calls for the "arrest" of those who push "fake accusations" against the Supreme Court nominee.

The "official" group defending Ford, meanwhile, had changed its name repeatedly over the past year. But its pivot from sports news to the Supreme Court on Sept. 27 drew confused reactions from members. While the group description currently claims it is devoted to "helping sexual abuse victims be heard," many of the comments on the group attacked Ford for allegedly lying.

"I love it when new people who are so much more informed and can speak more eloquently than myself put these bigots in their place. I have not enjoyed seeing women put down though," said McGuire, one of the administrators.

Facebook said recent policy changes allow only administrators of groups with more than 100 members to change their names once every 28 days. The rule is designed to prevent deception, the company said, although it appears some of the Kavanaugh-related groups have tweaked their names more frequently.

Still, for many political organizations, which rely on Facebook to recruit new allies and mobilize existing supporters, the rule aids their efforts. They can move from an issue like immigration to health care and still reach like-minded liberals or conservatives, who might want to see those perspectives anyway.

"Stop Kavanaugh Remote Rally" is one of the groups adopting such tactics. The hub is the brainchild of Action Together Massachusetts, a female-run organization that sought to rally Facebook users who are disabled or otherwise unable to physically attend a protest, said Kristin Olliney-Apruzzese, one of its team leaders. Before focusing on the Supreme Court, though, the organization had used the same group to plan an "online rally" of Trump's immigration policies. "We had members who were wanting to change it to Kavanaugh," she said, noting Facebook is a critical way for activists to "form an online community."

It's unclear exactly who is behind some of the other groups that have changed identities to support Kavanaugh or Ford recently, and ownership of groups can change easily. But malicious actors, including the Russian government, have exploited such vulnerabilities in the past. To that end, Rep. Frank Pallone, the top Democrat on the House Energy and Commerce Committee, on Thursday wrote Facebook, Google and Twitter to see if there had been evidence of foreign meddling in the online conversation about Kavanaugh. Pallone cited Facebook groups related to the nominee in his letter.

During the 2016 election, for example, one Facebook page tied to the Kremlin sought to lure unsuspecting users through an ad to click "like," and receive updates, about religious issues. Once they did, though, Russian agents then targeted them with politically charged content opposing then-Democratic candidate Hillary Clinton, according to documents released by Facebook last year.

Group owners "can attract a whole group of people to these kinds of groups overnight [on] a particular issue ... and change it to something that's perhaps far more political, far more partisan," said Dipayan Ghosh, a former privacy policy adviser at Facebook and current fellow at the Shorenstein Center on Media, Politics and Public Policy.