Washington (CNN) Nevada Sen. Dean Heller is set to attend a town hall Monday in Reno -- but he's not thrilled about it.

"It's gonna be a long day, to say the least," Heller -- perhaps the Senate's most endangered Republican in the 2018 midterms -- said at a fundraising lunch Wednesday. Audio and video recordings of his comments are being circulated by Democrats.

"Two hours of town hall meeting -- two hours of people yelling at you -- it's going to be quite the experience," Heller said. "But it's one of those boxes you gotta check."

Many other Republicans in competitive seats, though, aren't checking that box.

With members of Congress at home for a two-week spring break, many Republicans -- especially those in competitive states and districts -- are once again encountering backlash over President Donald Trump and House leadership's push to repeal the Affordable Care Act.

Two top Democratic targets in the 2018 midterms -- Reps. Leonard Lance of New Jersey and Mike Coffman of Colorado -- faced rowdy crowds Wednesday night. Lance was loudly booed for suggesting that Planned Parenthood divide itself into separate organizations -- one that performs abortions and one that offers other health services.

Some lawmakers, though, are opting not to hold town halls at all.

Virginia Rep. Barbara Comstock skipped two "mobile office hours" sessions she had scheduled in late January, as backlash against Trump and the GOP effort to repeal Obamacare began to build.

Hundreds showed up at a February "empty chair" town hall -- one organized by constituents to which the lawmaker was invited, but not confirmed to attend -- for Rep. Erik Paulsen of Minnesota, whose district Hillary Clinton won by nearly 10 points in the fall.

Aides for Comstock and Paulsen didn't respond to CNN's questions about why they haven't held town halls. But other GOP lawmakers have been blunt in arguing that the events attended by hundreds of constituents hold little value.

Rep. Mimi Walters of California -- whose Orange County district is similar to many Democrats hope will become hyper-competitive in 2018 -- said she sees town halls as political ambushes.

"The whole goal is to try to get as much press as they can, and then try to get me to say something that they could use against me in the campaign," Walters said in a recent interview on AM 870's "The Answer."

Some Republicans who aren't hosting town hall meetings say they prefer alternatives like "telephone town halls" where constituents call in, or in-person one-on-one or small-group meetings scheduled with constituents in their district offices.

Rep. Peter Roskam of Illinois, whose district Clinton carried by seven points, has opted for telephone town halls, small district offices and stops at local businesses and schools.

His spokesman, David Pasch, explained Roskam's reluctance to hold town halls in an email, saying that "large, unstructured events tend to devolve into shouting matches. Both sides compete with each over who can scream the loudest, while the people who are interested in an actual, productive dialogue are denied the opportunity to hear and be heard."

Rep. David Valadao of California, whose district Clinton carried by 15 points, is also opting for smaller-group events. "By utilizing a variety of methods such as community coffees, workshops, and telephone town halls, I am able to communicate with my constituents in ways that work for them," he said in a statement.

Rep. Dave Reichert, R-Washington, prefers one-on-one and small-group meetings, and has scheduled nearly 50 with more than 200 constituents, his spokeswoman Breanna Deutsch said. She said Reichert "believes this is the best way to maintain open communication with his constituents and have productive conversations."

But progressive groups argue lawmakers like Roskam, Valadao and Reichert are ducking accountability.

Indivisible, the group with more than 6,000 affiliates nationwide, recently published a new guide to "sham town halls."

"Telephone town halls are very controlled in that questions are screened, people are very easily cut off from asking any follow-up questions and it really gives the member of Congress too much control over the situation," said Sarah Dohl, Indivisible's chief communications officer.

Other forms of "sham town halls," she said, include events with narrow focuses -- such as "veterans' town halls" -- that are designed to discourage non-veterans from attending, and events where questions are sought in writing and then sorted and chosen by lawmakers' staffers.

Participants should keep their questions vague when speaking to a screener on telephone town halls, she said.

And in-person, Dohl said, "we're telling people that if they're in a situation where a member of Congress is reading questions from cards, they should feel empowered to stand up in the crowd and say, 'that one was mine' -- to say it out loud, to ask follow-up questions, and if the member of Congress is going on and on, to demand a yes or no."

To be sure, some Republicans in competitive seats are holding town halls. In addition to the Coffman and Lance events Wednesday night, Rep. Jeff Denham of California has one scheduled for Monday. Rep. Ryan Costello of Pennsylvania held one Saturday . Rep. David Young of Iowa has scheduled several across his district south of Des Moines.

Another Republican senator facing a potentially tough re-election contest, Arizona's Jeff Flake, is set to hold a town hall Thursday night.

On Monday, Heller, at least, will have backup: His town hall is a joint event with Republican Rep. Mark Amodei. Heller said at the Wednesday lunch that "I chose to do it with Amodei 'cause he'll do all the talking."

Other Republicans are ducking the topic of town halls altogether.

Aides for several GOP lawmakers in districts Clinton won in 2016 -- including Reps. Carlos Curbelo and Ileana Ros-Lehtinen of Florida, Ed Royce and Dana Rohrabacher of California and Kevin Yoder of Kansas -- did not return CNN's requests for comment on whether they intend to hold town halls.

An aide to Rep. Robert Pittenger, R-North Carolina, took a more confrontational approach.

Asked whether he plans to do so, Pittenger's communications director Jamie Bowers wouldn't answer. Since CNN hasn't covered Pittenger's town halls in previous years, he said, "why should we be interested in this question?"