It should be possible, even in these polarized times, to make a limited bipartisan deal on immigration.

Almost all Democrats and most Republicans agree that people who came illegally to this country as minors should generally be allowed to stay here legally. Most Democrats and almost all Republicans say that they favor better enforcement of laws against illegal immigration. So a deal that combines amnesty for the relevant subpopulation of illegal immigrants with increased enforcement measures ought to be doable.

Neither side would get everything it wants. Liberals would not get a broader amnesty that includes illegal immigrants who came here as adults; conservatives would not get a reorientation of legal immigration policy to favor the recruitment of high-skilled workers over the reunification of extended families.

But each side would achieve an objective. And since a major drawback of an amnesty is its potential to bring forth more illegal immigrants, the combination of a limited amnesty and increased enforcement makes sense. But there are two obstacles.

The first is that Democrats keep moving left on immigration. They are more and more hostile to deportation, which is to say to enforcing U.S. immigration laws. Their hardened stance, combined with their general aversion and opposition to President Donald Trump, makes them loath to agree to a down payment on a border wall as part of any deal.

The second obstacle is that Trump does not appear to have any fixed position in these negotiations or to understand the positions of others. His pattern so far has been to agree to the Democrats’ maximal demand — pass an amnesty with no conditions — and then let his aides start walking him back toward conditions, sometimes unrealistic ones.

During a televised meeting on Tuesday with Republican and Democratic lawmakers, Trump did not grasp that Democratic Senator Dianne Feinstein was asking for an amnesty bill with no enforcement provisions. House majority leader Kevin McCarthy had to bring the president’s attention to this point of contention.

Trump ended the meeting by saying he would be happy to sign any bill that Congress produced. If that position sticks, it will make it harder for Republican leaders to insist on meaningful increases in enforcement. Without these conservative provisions they will probably not have enough Republican votes to pass a deal.

If, on the other hand, White House aides again explain that notwithstanding all appearances their boss was really insisting on conditions, we’ve just skipped backward two steps in the process. It is not entirely clear why the meeting was held and televised; perhaps to prove that White House meetings don’t look like footage of the Gorilla Channel.

A limited agreement would be good for the illegal immigrants affected and for the country. What we seem destined to see instead is the art of no deal.

Ramesh Ponnuru is a Bloomberg View columnist. He is a senior editor at National Review, visiting fellow at the American Enterprise Institute and contributor to CBS News.