They voted to repeal Obamacare. Now they are a target.

For months, protesters have been rallying outside Sen. Cory Gardner's offices in Colorado, urging him not to join fellow Republicans in their push to repeal the Affordable Care Act. When he refused to hold town hall meetings, protesters staged them in his absence, asking questions to a cardboard cutout of him.

Now they are escalating their tactics.

With the controversial Republican health bill heading to the Senate, organizers of opposition groups say they plan to bird-dog Gardner's whereabouts and show up at his events, buying seats at fundraisers if necessary. They want to remind him that he promised to protect the expansion of Medicaid and guarantee coverage for people with pre-existing conditions, both provisions undone by the bill the House narrowly passed last week.

"I'm really angry right now," Katie Farnan, an organizer of Indivisible Front Range Resistance, said. "It seems like they're out to destroy the country."

Grass-roots groups around the nation have pledged to confront their members of Congress more intensely than ever in the hope of stopping the bill in the Senate, where Republicans have expressed concern about the millions of Americans expected to lose health insurance coverage or benefits if the bill is passed in its current form. And they are looking ahead to the midterm elections next year, vowing to punish Republican House members who voted in favor of the American Health Care Act, the formal name for the bill.

"Recess is from now to 2018," said Angel Padilla, policy director for Indivisible, an umbrella of national groups including Front Range Resistance. "This is what has been driving a lot of our groups out, it's been the focus of the town halls, and it's not over. This vote is only going to motivate them more as it continues to play out."

With the House on a recess this week (the Senate goes home later this month), few members have scheduled town hall meetings that are often the staples of trips back to their districts. Protesters are promising fireworks for those who plan to have sessions — including Rep. Tom MacArthur of New Jersey, a moderate who negotiated an amendment that secured the support of members of the conservative Freedom Caucus by weakening insurance regulations, including protections for people with pre-existing conditions.

"Everyone who voted for this has to feel like they're walking into a political buzz saw," organizers of Indivisible Colorado wrote in "Make Them Shake," a guide created after the vote last week. It urged protesters to donate to challengers of two incumbent Republicans, Mike Coffman and Scott Tipton, and to groups hiring Latino organizers to help get out the vote.

"Let's show the Senate we're just getting started," the organizers wrote, "that what we're about to do to the House GOP for this vote is exactly what'll happen to them next."

History and the numbers are daunting. More Republicans than Democrats tend to turn out for midterm elections. Democrats are also in an uphill battle because they are defending seats that are up for re-election in the Senate next year.

Still, organizers say there is a palpable sense that the vote by the House will fire up energy toward their ultimate goal: flipping seats to Democrats, particularly in the 23 Republican districts where Hillary Clinton won in November. After an earlier version of the bill failed to even come to a vote, some groups had worried that their victory came too soon. The passage of the House bill restores an issue that has been a unifying force for their movement.

Across the country, House members arrived home to protests. Many groups were offering training sessions for members on how to canvass for votes and how to run for office.

"It's increasing the amounts of energy," said Lise Talbott, a founder of Stanislaus Resistance in the 10th Congressional District of California, where Rep. Jeff Denham, a Republican who voted for the bill Thursday, won re-election in November by 4 percentage points — or about 10,000 votes.

Members of the group videotaped Denham at a town hall in April pledging to vote no on repeal. "There's a lot of sentiment that he lied to us," Talbott said. Her group has begun trying to increase voter registration by Hispanics and is working to get registered Democrats who have not traditionally turned out on Election Day to vote.

"People in the community understand the impact of this vote," Talbott said. "There are 300,000 people here with pre-existing conditions. That's everybody's family."

In Kansas City, Kansas, dozens of protesters gathered outside the office of Rep. Kevin Yoder, another Republican House member in a district won by Clinton, as the House voted Thursday. Yoder, like dozens of others, said he was undecided in the hours leading up to the vote. He voted yes.

"We hoped he would show the courage to do the right thing," said Hannah Williams-Touch, one of the organizers of the protest. "Once again, he proved politics over people."

A group went into his office to express its disappointment, she said and left a message for Yoder with the workers there. "We told him that this proves his seat is in grave danger in the next election. We plan to keep the pressure on."

In Wheaton, Illinois, protesters gathered outside a Republican fundraiser at a golf club, warning Rep. Peter Roskam that his seat, too, was in danger because of his yes vote.

Jessica Vealitzek, an organizer of a group called People over Politics, said leaders of the group were looking for candidates to run against Roskam. Their next monthly meeting will feature a speaker to train people in canvassing and volunteering for campaigns.

"He claims he's been hearing more people in favor of it, but I don't see people out on the streets advocating for the AHCA," Vealitzek said, using an abbreviation for the Republican health care plan. "It's hard to believe that he's telling the truth."

The resistance groups felt some measure of victory in the no votes from 20 House Republicans last week. In Colorado, for example, Rep. Mike Coffman voted no after weeks of protests outside his office. "Now our attention turns to Gardner," said Michael Himawan, an organizer of an Indivisible group in Coffman's district. "We can't allow the bill as it is to pass the Senate."

Republicans who voted yes, often after weeks of refusing to take a position on the repeal bill, faced new wrath.

"I feel a pivot," said Debra Caplan, a founder of NJ-11th for Change, a group that for months has turned out hundreds of protesters each week outside the New Jersey offices of Rep. Rodney Frelinghuysen, the powerful chairman of the House Appropriations Committee.

Frelinghuysen opposed an earlier version of the health bill in March, expressing concern about its cuts to Medicaid coverage, but Republicans pulled that bill before the vote. Many members of the activist group hoped he would vote no again Thursday, because the same Medicaid reductions remained in the bill. Frelinghuysen voted yes, prompting 120 protesters to appear in a driving rain outside his district office in Morristown, New Jersey, on Friday morning.

"I think that there were a good number of people who thought he'd vote no," Caplan said. "I think all of that goodwill has been erased by this vote. There are a lot of people who were not interested in replacing him who are very much there now. There are a lot of people saying this is the last straw."