DALLAS — This fall, dozens of members of Congress introduced or signed on to a pair of non-binding House resolutions focused on preserving a version of one of Obamacare's signature protections: a guarantee of coverage for individuals with pre-existing conditions.

Most of the members had a few things in common, beyond their decision to go all-in on the issue in the campaign's closing weeks. They were Republican. They had voted, repeatedly, to repeal the Affordable Care Act, the law that forces insurers to take on customers with pre-existing conditions with no added charge to their premiums, and last year voted for a replacement bill that would weaken that guarantee. And many — including Rep. Pete Sessions, R-Texas, the author of one of the measures — had found themselves locked in the closest races of their congressional careers.

They aren't alone. With polls suggesting most Americans overwhelmingly support Obamacare’s protections for those with pre-existing conditions — one survey from the Kaiser Family Foundation last month found that three-quarters of those polled want to keep them in place — Republicans in many of this cycle’s most competitive contests have embraced a similar message in the midterms home stretch, pledging their support for the idea on debate stages, in campaign ads and trail appearances.

But so far it's not clear the change in Republican politics has been matched by a shift in policy. The House resolutions offer few details, and conservatives have rebelled against prior efforts to keep existing ACA protections. A new Senate bill would require companies to provide coverage to all customers, but could open the door to charging more for their treatments. And right now, Republican officials in 20 states, including some running for higher office, are backing a lawsuit that would undo the ACA entirely.

Some, like Sessions, are invoking personal stories of their own family's struggles. Asked during a debate last week whether his plan would cover those with pre-existing conditions, Sessions had a ready answer.

"Matter of fact, it does," said the 11-term Dallas-area congressman said, adding: "I have a 24-year-old Down syndrome son." At least 20 Republicans have signed onto the non-binding measure he introduced, including several other vulnerable incumbents.

Missouri’s Josh Hawley, running against incumbent Democratic Sen. Claire McCaskill, is one of several GOP state attorneys general sounding a similar note on the trail despite signing on to the Texas-led suit to overturn the ACA, including its protections for individuals with pre-existing conditions.

“Earlier this year, we learned our oldest has a rare chronic disease, pre-existing condition," Hawley said in a recent ad. "I support forcing insurance companies to support all pre-existing conditions.”

In Wisconsin, Gov. Scott Walker is running ads supporting that protection for individuals while backing the same lawsuit to eliminate Obamacare. In Arizona — home to Rep. Martha McSally, one of the 217 Republicans to vote for the House GOP’s health care bill last year — Vice President Mike Pence plugged her Senate bid with the pitch that she had “fought to protect pre-existing conditions for every American. I was there. I saw it."

And in Wisconsin, Leah Vukmir — who is running against incumbent Sen. Tammy Baldwin, D-Wis., on a platform of "full repeal" of Obamacare — insisted during a debate earlier this month that she would “fall in front of a truck before I would let people go without coverage for pre-existing conditions.”

In recent weeks, the nation's top Republican has repeatedly stressed the same message, even as the White House has backed legislation and legal action that would partially repeal or entirely eliminate those protections.

"We will always protect Americans with pre-existing conditions. That’s a major part of what I’m all about," President Donald Trump said in Philadelphia earlier this month, days before writing in a USA Today op-ed article that he had campaigned on those protections, and falsely claiming that he had "kept that promise."

Campaigning in September for West Virginia Senate candidate and current state attorney general Patrick Morrisey, who has also signed on to the suit to overturn the ACA, Trump told a rally crowd that “pre-existing conditions are safe.”

But the White House supports the Texas lawsuit as well, though it has argued the courts should act more narrowly — by ending the law’s protections for people with pre-existing conditions. The Trump administration has also sought to expand the use of short-term insurance plans, which do not have to cover pre-existing conditions.

Former President Barack Obama, campaigning for Democrats at a rally Friday in Milwaukee, Wisconsin, pushed back hard.

"Making stuff up. Calling up, down. Calling black, white. ...that's what Republicans in Congress are doing all across the country on this pre-existing condition thing. They're running ads everywhere saying, 'we're the ones protecting it,'" he said.

"...[Trump] says 'I’m going to protect your pre-existing conditions' while his Justice Department is in court right now trying to strike down those protections," he added. "That is not spin. That's not exaggeration. That's not trying to put a positive glow on things. That's lying."

Congressional candidate Colin Allred speaks with an attendee at a fish fry hosted by the Dallas County Democratic Party in Dallas on Oct. 19, 2018. Cooper Neill / for NBC News

In Texas, Sessions' Democratic opponent had a similar take.

“I think that Pete Sessions’s non-binding resolution to protect pre-existing conditions that he put out a couple of weeks ago is just the worst kind of cynical Washington politics that people are so sick of,” Colin Allred told NBC News earlier this month at a fish fry sponsored by the Dallas County Democratic Party. “When you have a record in which you have voted over 50 times to take away those protections and then you try to pass a non-binding resolution to say that you stand for them, I think people can see through that.”

Sessions' vote to repeal the Affordable Care Act with no replacement, said Allred, backed eliminating coverage guarantees for individuals with pre-existing conditions. And his vote for the House GOP's replacement bill would have created waivers for states to allow insurers to dramatically increase premiums for individuals with pre-existing conditions if they failed to maintain continuous coverage. Other changes, like freeing insurers to sell plans that cover fewer areas of treatment and charge older customers higher premiums, would have effectively raised costs for sicker patients with more expensive needs.

The nonpartisan Congressional Budget Office estimated that under that bill, 23 million fewer Americans would have insurance and that, in states that waived Obamacare’s regulations, “less healthy individuals (including those with pre-existing or newly acquired medical conditions) would be unable to purchase comprehensive coverage with premiums close to those under current law and might not be able to purchase coverage at all.” The House passed the bill, but the Senate failed to pass its own version.