In the hours immediately after Wednesday's mass shooting in Parkland, Fla., Rosalind Holtzman of Elkins Park was angered to read a report that one of her U.S. senators, Republican Pat Toomey, had taken nearly $80,000 in donations from gun-rights groups in narrowly winning re-election in 2016.

It wasn't the first time that Holtzman, 59, has felt displeasure with Toomey. Since late 2016, she's taken part in the Tuesdays with Toomey movement that protests outside the senator's office in Philadelphia and elsewhere, urging the senator to reject conservative policies while pleading for an open, accessible town-hall meeting with him. When Toomey went on his Facebook page to express his thoughts and prayers for the victims in Florida, Holtzman posted an angry retort.

"While you're busy chest-thumping and fear-mongering about 'dangerous sanctuary cities.' children and adults are dying every day from gun violence," she typed. "The shooters in mass killings are overwhelmingly white American citizens. Yet you are content to do nothing, other than offer useless thoughts and prayers. The overwhelming majority of people in this country support common sense restrictions on guns."

But Toomey never saw Holtzman's Facebook plea. In fact, no one did. When the Montgomery County woman looked back at the senator's Facebook page, her post on gun control had been marked as "spam" and was not visible. And that wasn't a one-time occurrence, either for Holtzman or at least a half dozen other Tuesdays with Toomey activists who say their posts criticizing the Republican, or urging people to come to their protests, have been blocked for the same reason. Holtzman told me that "you're basically being erased."

Here's the thing: Toomey's staffers tell me that — while they're aware of the problem — they have nothing to do with it. They blame Facebook.

"There is no staff-led effort to delete posts that voice disagreement or those that are not obscene but are critical in nature," Toomey's spokesman Steve Kelly told me in an email. "If you do not believe me, take a look at the comments on Senator Toomey's various Facebook posts." He said Toomey staffers even reached out to Facebook and learned that the social media giant is simply trying to crack down on actual spam by flagging certain kinds of posts, with links. or when someone repeatedly writes the same message.

Welcome to the new paranoia in American politics.

The rise of social media — especially Facebook and Twitter — once seemed to offer a new opportunity for elected officials and other leaders to connect directly, and more frequently, with their constituents, but like many promises of the Internet age it hasn't exactly worked out that way. Increasingly, politically active citizens complain that officials who have been limiting old-fashioned in-person contact, like town hall meetings, are now embracing newfangled methods where voters find themselves electronically blocked — sometimes accidentally, sometimes intentionally.

In what until this week was Pennsylvania's 6th Congressional District in Philadelphia's far western suburbs, the American Civil Liberties Union (ACLU) of Pennsylvania has been probing multiple complaints that GOP Rep. Ryan Costello has been blocking constituents from the congressman's official Facebook page for fairly mundane political complaints, like calling out Costello's campaign contributions from Comcast. Costello's spokeswoman told my colleague Holly Otterbein that "his Facebook page has included a clearly stated policy of engagement."

Nationally, episodes of powerful pols blocking everyday citizens have been even more outrageous. Some constituents in Arkansas reported receiving actual "cease-and-desist" letters from Sen. Tom Cotton, whose spokesman acknowledged the letters but insisted they were rare and only sent in the case of a perceived threat. Even President Trump — whose preferred mode of communication is clearly Twitter — is under fire for blocking ordinary citizens who've dared to disagree with him. Seven Twitter users have sued the president, claiming he's violated their First Amendment rights by blocking their access to public communications from the commander-in-chief.

Witold J. Walczak, the legal director of the Pennsylvania ACLU, said blocking critics on social media is a growing problem, and that the group recently lodged complaints against a Pittsburgh city councilwoman and a Lackawanna County commissioner for that practice. He called it "a form of censorship — you can't just leave people up who love you, and then censor people who are critical."

It's especially important, he added, because increasingly members of Congress and other elected officials seem to be cutting back on what used to be the best way to get feedback from their constituents, in-person events such as town-hall style meetings. "Like every other aspect of our life," Walczak said, "social media has become not the dominant but one of the preeminent forms of communication."

In a way, the current climate of frustration, paranoia and ill will isn't that surprising. After all, this decade has seen two separate assassination attempts that seriously wounded members of Congress — including the 2011 shooting of Arizona's Gabby Giffords at a meet-and-greet event for her constituents. You certainly can't blame a representative like Costello — who just missed his ride or would have been on a Virginia softball field last summer when a gunman started firing, wounding his colleague Rep. Steve Scalise of Louisiana — for taking real threats seriously. But too often safety concerns seem to be an excuse for squashing legitimate discourse.

Facebook isn't really most citizens' top choice for talking to their representatives, anyway. One reason the Tuesdays with Toomey group has kept up its momentum is its fury with the senator for not having easily accessible town hall meetings — including never in Philadelphia during his seven-plus years in office. The options for direct interaction with a member of Congress — brief "telephone town halls" where callers can be screened, or invitation-only or lottery-limited public events — seem to keep dwindling.

In the end, whether it's Facebook or Toomey staffers marking messages as "spam" isn't as important as the fact that social-media democracy is a poor substitute for real democracy.