Activists cheer as a new mobile electronic billboard to help them unseat Rep. Barbara Comstock (R-Va.), passes by on the Leesburg Pike in Sterling, Va., on June 22. (Bill O'Leary/The Washington Post)

For several hours one morning last week, a truck sporting 6-foot-tall electronic signs admonishing Rep. Barbara Comstock (R) to “Do your job Hold a Town Hall” cruised around her Northern Virginia district while some drivers honked their approval.

“Hey, there it is!” shouted a protester waiting for the truck on the grassy strip between a busy road and a shopping centerthat is home to Comstock’s district office in Sterling.

The mobile billboard is the latest stunt dreamed up by Sean Schofield, a 44-year-old computer programmer from Silver Spring, and Abbey Ruby, a 34-year-old lawyer from McLean, who have been needling Comstock for months with a snarky website, social media strikes and ambushes caught on video.

That Comstock faces opposition in a district where Hillary Clinton defeated Donald Trump by 10 points is no surprise.

But the aggressive tactics employed by the group, called Dump Comstock, and its single-minded focus on embarrassing the two-term congresswoman more than a year before the 2018 election are highly unusual in this district.

Activists gather in Sterling, Va., to see a new mobile electronic billboard that advertises the “Dump Comstock” effort to unseat Rep. Barbara Comstock (R-Va.) (Bill O'Leary/The Washington Post)

Through a spokesman, Comstock declined to answer questions about the group.

It’s impossible to know whether Dump Comstock will make a difference by the midterm elections, but Democrats and Republicans say it has provoked activists on both sides and suggests that the midterm races could get nasty.

“This is a lot more energy than we’ve seen for this race this far ahead of time probably in my lifetime,” said Zach Pruckowski, 30, chairman of the 10th Congressional District Democratic Committee. “They’re certainly making a lot of noise.”

The race is a top target for national Democrats even though Comstock won reelection to a second term by six points last year and defied predictions that sharing a ballot with Trump would damage her chances.

John Whitbeck, chairman of the Virginia Republican Party, engages with Dump Comstock online and reads Schofield’s “mean tweets” at GOP meetings — editing out the profanity.

“To be honest with you, they’re fun to play with on Twitter but we don’t take them all that seriously,” he said, calling Dump Comstock “a fringe, extremist group.”

Schofield said he understood the importance of the district, formerly held by Republican congressman Frank Wolf, when he showed up in Bethesda in 2008 to volunteer for Barack Obama and was dispatched to Manassas. Eight years later, he returned to Comstock’s district to knock on doors and register voters for Hillary Clinton.

He attended the Women’s March with his wife and son and was inspired to start Dump Comstock. His idea was to create enthusiasm for flipping the congressional district long before the major parties, preoccupied with the Virginia governor’s race, were focused on midterms.

Applying his experience as the founder of an e-commerce software company, Schofield created a website and social media accounts based on the idea that voters should break up with Comstock. That led to the name (tag line “It’s not us. It’s her”) and eventually a red-and-blue broken-heart logo. Today there are buttons, bumper stickers and yard signs.

To gain followers early on, Schofield looked for critics of Comstock who had posted on her Facebook page. He sent them private messages, the online version of a cold call, and invited them to join the group.

About 1,400 people are members of the Facebook page and, using the organizing tool Action Network, he estimates about 20 percent live outside Comstock’s district, in Maryland and the District, although Comstock supporters suspect that figure is higher.

Schofield, who tweets at @uberzealot, said living in Maryland doesn’t undermine his mission because federal decisions affect everyone.

“It’s not another planet,” he said. “What Barbara Comstock does affects me just as much as what [Montgomery County Democratic Rep.] Jamie Raskin does,” he said.

Dump Comstock is working with other groups seeking to unseat Comstock, including Planned Parenthood, the Service Employees International Union (SEIU) and Indivisible. They want to amplify Democrats’ discontent in the Trump era and channel it toward the only swing district in the region.

Ruby is treasurer of Dump Comstock’s political action committee, Take Back the Tenth, which has not yet reached a filing deadline to report its donors. She said it collected about $8,000 to hire the truck, which is also booked for the July 4 parade in Leesburg.

“Comstock shows up with 20 high school kids in T-shirts with balloons and big totem signs,” Schofield said. “And we figure we can’t let that go unchecked.”

Interactions with the group can escalate quickly.

A man who identified himself as a constituent approached Comstock at the Lovettsville Mayfest to question her, while another person recorded the encounter — video that was posted to YouTube by Dump Comstock.

During the tense exchange, the man asked Comstock to hold a town hall. She said she preferred to meet with constituents at her offices or in other smaller settings like her booth at Mayfest.

“We’re talking to people instead of, you know, being harassed,” she said, and walked off.

Schofield considered it a milestone when Comstock’s campaign Twitter account responded to his website’s claim that she missed two recorded votes to join Trump in the Oval Office when he signed a bill she sponsored.

“It’s simple — always pleased to have my bills signed into law. Attended bill signings with Gov. McDonnell and Gov. McAuliffe too,” the tweet said, referring to her time in the legislature with a photo.

Early Thursday at a McLean park where the billboard truck prepared to start its rounds, three of the 12 people who showed up were candidates or there on behalf of candidates challenging Comstock. Seven people have either filed paperwork to run or indicated that they intend to.

No one seemed to notice that the truck was parked directly next to a handicapped space in an access aisle painted with diagonal white lines, a blunder clear in photos online.

When questioned by the Loudoun County GOP, Dump Comstock responded: “Space doesn’t looked blocked to the rest of us.”

“Because you don’t care about anyone except yourselves. A van would have trouble opening a door. That’s why the white lines are there,” the Loudoun County GOP wrote.

To Schofield, it’s all gravy because anytime Republicans are responding to him, he said, they’re not defending Comstock.

“They can’t help themselves,” he said. “They’re falling into our trap.”