Continued from page 1

Mr. Romney discovered that two years ago when he struggled to explain why state health care reforms he shepherded in Massachusetts did not jibe with Mr. Obama’s approach, even though “Romneycare” served as a template for the national law.

Mr. Perry should have no problem selling his stance on Obamacare to conservative primary voters. He has called the law a “stomach punch” and a “monstrosity.”

But a general election contest could offer questions about whether Mr. Perry did enough for Texas’ large uninsured population, as some in the Lone Star State find their incomes too high for Medicaid but too low to qualify for subsidies on the federal health care exchange. The gap results when state leaders refuse to expand Medicaid.

Mr. Walker took a Solomonic path to close such a gap. While rejecting Obamacare’s expansion, Wisconsin made sure its Medicaid program covered everyone up to 100 percent of the poverty line, the threshold to qualify for Obamacare subsidies.

“We provide health care access to everyone living in poverty, help transition those above poverty into the marketplace, reduce the number of uninsured and limit the future risk to Wisconsin taxpayers,” Mr. Walker told the Milwaukee Journal Sentinel this month for its series on gubernatorial candidates.

Indiana Gov. Mike Pence, a Republican whose name is sometimes bandied about in 2016 chatter, has sought a federal waiver to expand Medicaid through a set of market-oriented reforms that emphasize personal responsibility. This way, his state can leverage federal funding without making it look like he is embracing Obamacare.

Some conservatives have called out Mr. Pence on the plan, but the flip side could be worse: Will voters accept candidates who flout Obamacare but have no health care reform plan of their own?

“If you’re going to run for president of the United States, voters expect you to have a set of fairly specific proposals on a variety of issues that affect the nation,” said G. Terry Madonna, a politics professor at Franklin & Marshall College in Lancaster, Pennsylvania.

In April, Mr. Jindal rolled out a blueprint to repeal and replace Obamacare. The plan reflected the Louisiana governor’s experience as a health care policy prodigy in the 1990s and elevated him among potential presidential contenders.

The blueprint relies on states to set up their own reforms. A grant pool of more than $100 billion would be doled out over the next decade to let states subsidize insurance for low-income residents and, as a precondition for the funding, make sure people with pre-existing health problems are not denied coverage.

Having a plan in hand would allow Mr. Jindal to be more aggressive during primary debates, Mr. Gerow said, which is “where this issue comes to the fore.”