In theory — as stipulated by President Trump countless times on the campaign trail and as reiterated by him on Twitter over the weekend — the construction of a large wall on the United States’ southern border will be paid for by the nation of Mexico. At no point in time has Trump offered a politically feasible explanation for how that payment will occur; in a tweet Sunday, he was more nebulous than normal.

“In some form” Mexico will pay “eventually.” But in a concrete form, Americans will pay now: with revenue collected from your income taxes.

That is, assuming that Trump’s team can persuade Congress to allocate the necessary funding. Congress has not been particularly eager to do so. Therefore, last week, budget director Mick Mulvaney introduced a new strategy from the administration. For every dollar that Congress approves for building the wall, Trump will accept a dollar spent on paying insurers to subsidize health care under the Affordable Care Act. Government funding is central to the Affordable Care Act’s viability, and if the administration were to oppose that funding, the health-care program would be severely undercut. In other words, the administration hopes to use Democrats’ support for the Affordable Care Act — Obamacare — as leverage for getting them to approve funding for the wall.

The political challenge here? Obamacare is quite a bit more popular than Trump’s wall.

Over the course of 2016 and into this year, Obamacare’s popularity increased. Polls gathered by Huffington Post Pollster show that rise over the past 12 months or so, a function in part of the increased threat posed to the program by unified Republican control of Washington.

The Kaiser Family Foundation has been polling on the legislation since it was passed. In April 2016, 38 percent of the country had a favorable opinion of the Affordable Care Act; by this month, the figure had jumped to 46 percent. In fact, in March, nearly half the country viewed the Affordable Care Act positively.

Unsurprisingly, there’s a split in the views of Democrats and Republicans on the subject. In April, 74 percent of Democrats viewed it positively. In March, at the peak of support since July 2010, nearly 1 in 5 Republicans viewed the legislation positively. (In April, that fell to 15 percent.)

Compare that with polling on Trump’s wall. Both CNN and Quinnipiac University asked Americans if they thought that funding for the wall should move forward. In early March, 39 percent of respondents agreed that it should, according to CNN (and its polling partner ORC).

The strongest support was offered by those who said they’d voted for Trump. Three-quarters of Republicans agreed that the funding should be a priority. However, only a third of independents and about 1-in-10 Democrats agreed that the spending should happen.

In late March, Quinnipiac found that only 35 percent of Americans felt that wall spending should move forward. Again, most Republicans agreed, but only 31 percent of independents and 6 percent of Democrats agreed.

In other words, polling in March showed that 49 percent of Americans supported Obamacare to 39 percent who wanted to spend on the wall, according to the higher numbers in that CNN-ORC poll. About 45 percent of independents viewed Obamacare positively, but only 34 percent of that group wanted to spend on the wall. Given that soft support from independents is one of the main reasons Trump’s approval rating is historically low, that seems significant.

An interesting Fox News poll from last month asked people to rank what they hoped Trump would accomplish. Even among Republicans and Trump voters, building the wall was a lower priority.

We’re comparing a few kinds of apple here, of course. But generally, polling suggests that Obamacare is more popular than the wall, with every group except Trump’s core base of support. That’s probably part of what’s happening here: Because Trump’s focus from the outset of his campaign has been to appeal to the same central core of the American electorate, that he’s threatening something moderately popular on behalf of something fairly unpopular makes sense, given that opinions are flipped among the voters who pushed him over the finish line. Over the short term, that’s a low-risk strategy for Trump. Over the longer term? We will see.

What would make all of this easier, of course, is if someone else would step in and pays for the wall. Maybe it will happen eventually.