Jeb didn’t call for Obamacare repeal in his announcement. That’s big.

Jeb Bush laid out his top policies Monday in a speech announcing his run for the 2016 Republican nomination. But he left out one big Republican priority: repealing Obamacare.

While Mitt Romney kicked off his campaign in 2012 with a call for a “complete repeal of Obamacare,” Bush went more narrow, mentioning the law only in the context of his support for an order of Catholic nuns, Little Sisters of the Poor, that continues to challenge the health law’s contraceptive mandate.

The stark difference — from full repeal to narrow objection — reflects the changing politics of Obamacare. As Obamacare becomes more and more entrenched, it builds a constituency. As more people sign up for Obamacare, it becomes increasingly difficult to take away both practically and politically. So Republicans, who once ran and won calling for its end, are beginning to abandon the line.

Bush, a Catholic, made only one reference to the health-care law Monday. It wasn’t about the individual mandate or the subsidies — the two biggest Republican objections to the law — but an arguably narrower issue over contraception. Here’s what he said:

The most galling example is the shabby treatment of the Little Sisters of the Poor, a Christian charity that dared to voice objections of conscience to Obamacare. The next president needs to make it clear that great charities like the Little Sisters of the Poor need no federal instruction in doing the right thing.

Compare that with Mitt Romney’s much more forceful announcement of his 2012 run, which included this line:

I will insist that Washington learns to respect the Constitution, including the 10th Amendment. We will return responsibility and authority to the states for dozens of government programs – and that begins with a complete repeal of Obamacare.

Back in 2011, a frontrunner for the Republican nomination put his opposition to Obamacare front and center. Four years later, repeal is nowhere in sight.

And it’s no accident. Bush covered economics, education, foreign policy, and many other policies in his speech. He even spoke about immigration reform. Leaving out Obamacare repeal was as important a decision as what he included.

Back in 2011, when Romney announced, Obamacare was an abstraction with few beneficiaries.

There were certainly the Beltway advocates who had lobbied hard for the health law’s passage. And some young adults had signed up for coverage under their parents’ plans, after the law extended dependent coverage up to age 26.

But the health law’s big program — an expansion of insurance to millions of Americans — was still hypothetical. Nobody had actually signed up for Obamacare’s new insurance market, the one where preexisting conditions didn’t exist and insurers couldn’t exclude anyone. That market wouldn’t launch until 2014. Obamacare enrollees, back then, were about as numerous as unicorns.

When Romney talked about repealing Obamacare, there weren’t actual, real people who would lose their health insurance. And when the issue did come up — especially around coverage for Americans with preexisting conditions — Romney ended up scolded by fact checkers who disputed his claims that his replacement plan would keep them covered.

Now when Bush talks about Obamacare, there certainly are actual people involved. There are 10.2 million people signed up for coverage through Obamacare’s private marketplaces, and millions more covered under the law’s Medicaid expansion.

Writing in the Atlantic, David Frum argued that this could cause one question to dominate the 2016 election cycle: will you take away my health insurance?

For those economically stressed toss-up voters—for the younger voters who sometimes show up and sometimes vote—the tipping point issue won’t be foreign policy. It won’t be ethics. It won’t be healthcare. It won’t even be the overall performance of the economy, which will be better, but still unwonderful. It will be that single haunting question, “Will I lose my insurance?”

If they don’t hear a clear and convincing “No,” they’re going to assume the answer is “Yes”—and most likely, vote accordingly.

Romney never had to face those type of questions; nobody was around to ask them. But for Bush, more than 10 million people could ask that question — and that likely makes it much more difficult to stake out a pure repeal position.