The rumor ripping through Washington in recent days goes something like this: On the eve of Christmas—with the capital empty and Americans tuning out the news—President Donald Trump will announce the firing of Special Counsel Robert Mueller.

Trump said on Sunday that he has no plans to do so, but anti-Trump “Resistance” groups aren’t exactly taking his word for it.

Instead, many of those groups, who say they have been readying for the possibility of Mueller’s ouster for months, are now ramping up contingency plans and discussing what to do should Trump use the holidays to make such a decision. They’re also quietly prepping for other, less sensational moves from the White House, like the potential replacement of Deputy Attorney General Rod Rosenstein—the Justice Department official with the authority to end the special counsel’s investigation.

The warning from these groups to Trump: They’re ready. They also point out that the holiday season, despite its apparent advantages for anyone looking to bury some news under a pile of Yule logs, might actually be a terrible time to pull a fast one.

For starters, many Americas will already be off from work or home from school—and anyone who feels like they got plenty of family face-time in at Thanksgiving might be itching for an excuse to hit the streets. “Everyone is home together with their families for the holidays and ready to go out and protest,” said Elizabeth Beavers, policy manager for Indivisible, one of the most prominent groups formed to resist Trump.

Likewise, while the White House might see the Congressional recess as wonderful time to disrupt the Russia investigation—lawmakers would be unable to push back on any Trump-induced Christmas Eve Massacre—that could be risky, too. “Members of Congress are going to be at home in their districts seeing hell raised on their own home turf,” said Neil Sroka, communications director at the progressive group Democracy for America, which has been active in organizing for the possibility of Mueller’s firing.

Those preparations have ratcheted up in recent days as attacks against Mueller have grown louder among conservatives. Fox News has given voice to speculation that Trump is the target of a “coup,” and one of the network’s hosts, Jeanine Pirro, has endorsed the idea that FBI agents involved in Mueller's Russia probe should be arrested.

The rising animosity toward Mueller coincides with growing impatience at the White House, where Trump’s team has said it expects the investigation to conclude before the end of the year. That supposed and unrealistic timeline has led to speculation that Trump may feel empowered to make a big move soon.

On Friday, during a local television appearance in California, Democratic Rep. Jackie Speier shared the Capitol Hill rumor that Trump would announce Mueller’s firing in a speech this Friday, December 22. Former attorney general Eric Holder tweeted a call for mass protests in response to such a move.

Resistance groups are mobilizing. On Monday a coalition of activist organizations announced that signups had surged in recent days with more than 100,000 people pledged to turn out for some 500 events spread across the country. By Tuesday afternoon, an updated press release touted 135,000 would-be protesters gearing up for more than 600 events. That would include a recently announced protest in Grand Forks, North Dakota—which means events are now on standby in all 50 states and Puerto Rico, should Trump make a move.

According to David Sievers, a campaign director at MoveOn, one of the groups in the coalition, sign-making parties have already begun in some places. The groups have also been discussing a coordinated messaging strategy that will focus on pressuring Congress to act, according to Sroka. Resistance activists who will themselves be traveling over the holidays and had already pledged to host local protests in the event of a Mueller firing are now scrambling to lock down backup hosts if something goes down while they are out of town, according to Sievers.