Anti-choice activists, despite their concerted efforts, failed to bring Planned Parenthood to its knees by pulling its federal funding in 2015. But activists pledged to continue in 2016 to attack the organization from the inside.

On Thursday, the eve of the annual March for Life—when abortion foes from across the country march at the nation’s capital to protest legal abortion—activists rallied in front of an under-construction Planned Parenthood center in Washington, D.C. There, anti-choice leaders warned Planned Parenthood they are continuing to plot ways to try to bring it down.

“Be on your toes, because we are in your midst,” said Father Frank Pavone, the national director of the New York-based group Priests for Life, directing his comments toward Planned Parenthood. “The trouble for you has only just begun.”

Pavone told the crowd of roughly 70 shivering protesters on that icy morning that Planned Parenthood has not seen the last of the kind of undercover video project the Center for Medical Progress (CMP) produced last year. The California-based anti-choice front group edited the shortened versions of these videos to suggest that Planned Parenthood clinics illegally sell fetal tissue.

CMP produced no hard evidence to bolster this claim, and multiple Republican-led state and federal investigations against Planned Parenthood have yet to turn up evidence of wrongdoing.

Pavone noted that the organization Life Dynamics, based in Denton, Texas, which worked with CMP to carry out its smear campaign, will next month begin training activists to become intelligence operatives who infiltrate abortion clinics throughout the country.

Life Dynamics president and founder Mark Crutcher—who unsuccessfully tried to prove that Planned Parenthood sold fetal tissue in the late 1990s—will personally train groups of no more than 12 people two days a month through December. Life Dynamics’ website says applicants will be screened, lest the infiltrators become the infiltrated.

In Pavone’s words, Life Dynamics is training a “new army” of people just like David Daleiden, the founder of CMP.

“We are at your secret meetings,” Pavone said, addressing Planned Parenthood. “We are working with you, though you know not.”

Pavone acknowledged that so far no state or federal investigation has found Planned Parenthood guilty of illegally selling fetal tissue or aborting live babies, as Daleiden and his allies have frequently claimed. Pavone insisted that states will eventually prosecute Planned Parenthood with what he said is secret evidence they are guarding “behind closed doors.” He offered no proof or specifics to bolster this assertion.

Meanwhile, Planned Parenthood has gone on the offensive against some of these activists. Last week, it sued Daleiden and his CMP associates, charging the group with racketeering, civil conspiracy, fraud, invasion of privacy, and other criminal violations.

Daleiden spoke toward the end of Thursday’s rally, after Rewire had left. Freelance reporter Robin Marty reported on Twitter that Daleiden wore a “Racketeering for Life” pin he was gifted by another activist.

Speaking on Friday at the Family Research Council’s ProLifeCon Digital Action Summit in D.C., part of this week’s March for Life events, Daleiden doubled down on accusations that his group has made against Planned Parenthood and, like Pavone, predicted that state and federal investigations will one day prove him right.

He said Planned Parenthood has not answered questions his group has raised, such as how much money the health-care provider received in exchange for donating fetal tissue to researchers and whether it has performed illegal abortion procedures in an effort to obtain that tissue. He suggested these questions might be answered during the discovery portion of the lawsuit Planned Parenthood “so unwisely brought” against his anti-choice front group.

“Those answers are going to come out and that other shoe is going to drop,” Daleiden said. “I am very convinced and I am very hopeful that 2016 is going to be a watershed moment for abortion and for the pro-life movement. It’s going to be a watershed moment in our history for how we talk about unborn children and how we treat unborn children in our country.”

Planned Parenthood’s D.C. affiliate has similarly refused to back down in the face of anti-choice activists’ efforts to stop the construction of its new health center, which will offer abortion care and a range of reproductive and sexual health services.

Laura Meyers, president and CEO of Planned Parenthood of Metropolitan Washington, DC, promised in a press conference this week that the clinic would open as scheduled this year. Since the summer, activists have regularly protested the construction site, located next door to a public charter elementary school and across the street from the charter’s middle school campus.

Two Rivers Public Charter School in December sued some of these anti-choice protesters for allegedly harassing students and parents in front of the school, in some instances reportedly telling them a baby-killing center was moving in next door.

Meyers said during the press conference that these were acts of “shame and hate” and “not about free speech.”

Two Rivers canceled classes Thursday in anticipation of the protest, leading one angry parent, Bill Harper, to stop by and yell at the assembled crowd that they were the ones creating trouble for his kids.

He told Rewire he had to pay $80 for the day to send his 5- and 7-year-old kids to day care. He said since classes started in September, he has received about half a dozen calls from the school notifying them when anti-choice activists stage protests right outside school grounds.