A comprehensive plan could be a lightning rod for opponents. Conversely, not having a plan for replacing some of the most popular parts of Obamacare — such as its coverage protections for people with preexisting medical conditions — could leave the GOP flat-footed if an administration-supported lawsuit before the 5th Circuit Court of Appeals invalidates the sweeping health law.

"This is a real conundrum. There is a risk with action or inaction," said Dean Rosen, a Washington, D.C., health policy consultant who often advises Republicans.

No matter how the 5th Circuit rules, its decision, which could come soon, is likely to be stayed while the issue heads to the Supreme Court. Such a delay would give the administration time to flesh out a proposal if the appeals judges throw out the ACA, but it would also ensure that a health care debate is front and center during the presidential campaign.

Right now, polls show the public is focused on health costs, said professor Robert Blendon, who directs the Harvard Opinion Research Program, which studies public knowledge of health care and policy issues. Consumers are concerned about what they pay at the pharmacy counter or the sum of their insurance premiums and deductibles.

"Most voters are not interested in another debate on a new health plan," he said.

But if the 5th Circuit upholds a Texas ruling overturning the entire ACA, "that changes the entire framework," said Blendon. "The administration could not just say, 'Oh, we'll have something great.' They would have to have something outlined."

Supporters and critics say likely elements are already in plain sight, both in executive actions and proposals in the president's budget as well as a little-noticed white paper released late last year.

The president has won praise from both conservatives and liberals for such things as his proposals to require hospitals to post their actual, negotiated prices, and some strategies to lower drug prices. But legal battles within the health industry could thwart such initiatives.

On these topics, "a lot of what they've proposed has been pretty smart," said Shawn Gremminger, senior director of federal relations at the liberal Families USA advocacy group.

Still, Gremminger points to other administration actions — loosening rules on health insurers to allow sales of what critics call "junk" insurance because they don't have all the consumer protections of ACA policies, or promoting work requirements for Medicaid recipients — as strong hints to what might be in any eventual election-related plan.

"I think what we'll see is a lot of that same sort of stuff, warmed over and put into a new package," Gremminger said. "We fully expect it will include a lot of really terrible ideas."

For other policy clues, some advisers, like Brian Blase, a former special assistant to the president at the National Economic Council, said look no further than that little-noticed 2018 interagency report.

The 114-page document includes more than two dozen recommendations that broadly focus on loosening federal and state regulations, limiting hospital and insurer market power and prompting patients to be more price-conscious shoppers.

Many are long-standing Republican free-market favorites, such as increasing the use of health savings accounts, which allow consumers to set aside money, tax-free, to cover medical expenses. Other ideas are not typically associated with the GOP, such as increased federal scrutiny of hospital and insurer mergers, which have driven up prices.

The paper also calls for less restrictive rules for the Medicare Advantage plans that offer an alternative to the traditional fee-for-service Medicare. It would allow the advantage program to have smaller networks of doctors and hospitals — presumably ones that agreed to charge less.

"The administration knows where it is going on health care," said Blase.

If the court strikes down the ACA, he expects the administration to release a plan supporting "generously funded state-based, high-risk pools."

Such pools existed in most states before the ACA. They helped provide coverage for people with preexisting conditions who were denied policies by insurers. But the pools were expensive, so they often were underfunded, capped members' benefits and yielded long waiting lists.

Some think the white paper is not so much a plan as a "combination of policy ideas and political statements," said Joe Antos at the conservative-leaning American Enterprise Institute.

Still, he doubts the GOP needs a comprehensive health proposal. Republicans are more likely to gain politically by merely attacking the Democrats' ideas, he said, especially if the Democratic nominee backs proposals for a fully government-funded health care system, such as the "Medicare for All" plans some candidates support.

Republicans will "have their own one-liners, saying they are dedicated to protecting people with preexisting conditions. That might be enough for a lot of people," Antos said.

Politically, it's risky. While many voters don't understand all that the ACA does, some of its rules enjoy broad support. That's particularly true of the protections for people with medical problems — insurers are barred from rejecting them for coverage or charging them more than people without such conditions.

The Republican effort to repeal the law galvanized activists during the 2018 midterm elections and is credited with boosting Democrats to victory in many House districts.

Analysts on both sides expect concerns about health costs and the ACA to play a large role again in 2020.

For Republicans, "the risk of doing nothing potentially leaves no port in a storm if the ACA is overturned legally," said Rosen. "But a more limited version, which is what most Republicans are for, is likely to be met with the same concerns. No matter what the president says, it won't be enough for the Democrats."

Opinion poll analyst Blendon said there is an additional unknown: which Democrat will win the nomination — and what type of coverage he or she will back.

Even as the GOP is split on how to address health care concerns, so too are the Democrats.

"If they are reading the same polling data as I am, they would have serious proposals for lowering drug and hospital costs, but not offer a national health plan," said Blendon.

The Democrats' most progressive wing, led by Sens. Bernie Sanders of Vermont and Elizabeth Warren of Massachusetts, wants Medicare for All, which would essentially eliminate private and job-based coverage. Recent polls have shown voters are not keen to lose private insurance.

The party's center, led by former Vice President Joe Biden, wants to keep the ACA but apply "fixes" to make insurance purchased by individuals more affordable.

"If the Democratic nominee is running on keeping the ACA, the Republican will have to have an alternative," said Blendon. But, if the nominee supports Medicare for All, he predicts simply a GOP "anti-campaign" targeting the Democrat's idea as unworkable, socialist or a danger to Medicare.

Kaiser Health News is a nonprofit news service covering health issues. It is an editorially independent program of the Kaiser Family Foundation, which is not affiliated with Kaiser Permanente.

Read more: 

• Trump says GOP 'blew it' on health care and must run on new plan
• Forget Medicare for All, Americans want help with health care expenses
• Nonprofits look for health care reform, but maybe not Medicare for All