Four years ago, deep within a process of convincing Republican primary voters that he was "severely conservative," Mitt Romney declared that his solution for dealing with the millions of undocumented immigrants in the United States was "self-deportation" — in other words, making life so miserable for them that they'd prefer to return to the countries they fled from rather than stay here. The chairman of the Republican Party later called Romney's words "horrific," not so much out of some moral revulsion, but because they sent a clear message of hostility to Hispanic voters, the country's largest minority group and one that is growing fast. Since then, most Republicans have acknowledged that they have to be careful about how they talk about those 11 million immigrants if they want to have any hope of winning the White House again.

Then along came Donald Trump, who isn't careful about anything (other than that glorious and extremely delicate mane of hair). Barreling into the campaign, Trump said he'd deport all 11 million, then let "the good ones" return to the United States. How would the unfathomably complicated task of locating all those people, detaining them, and moving them back to their countries of origin be accomplished? "It's feasible if you know how to manage," he said. OK then.

Compared to Trump, the rest of the GOP candidates have been models of reason and thoughtfulness on this issue, and between them they've taken a couple of different positions on how to handle the undocumented. If comprehensive immigration reform ever happens, this will be one of its key components, so it's important to know where they stand.

But first, what about the public? Gallup just released a survey that sheds some light on this question, showing both why Trump is getting support and why most of the other candidates are taking a different tack. Asked whether the government should "deport all illegal immigrants back to their home country, allow illegal immigrants to remain in the United States in order to work, but only for a limited amount of time, or allow illegal immigrants to remain in the United States and become U.S. citizens, but only if they meet certain requirements over a period of time," a full 65 percent said they should be allowed to become citizens, and only 19 percent said they should be deported.

But right now, the GOP candidates aren't seeking the support of the whole country, they're going after the Republicans who might vote in upcoming primaries. Among Republicans, the numbers are different — but not as much as you might expect. Fifty percent of Republicans said there should be a path to citizenship, while 31 percent said they should be deported.

Thirty-one percent isn't a majority, but it's still a lot — and you could say the same about Trump's support in the polls. Right now he's averaging around 24 percent, and while there are certainly people supporting him who don't agree with him on immigration (and those opposing him who do), if you want the candidate taking the clearest anti-immigrant stance, your choice is pretty clear.

So where do the other candidates come down? When you ask them about a path to citizenship you'll inevitably get a complicated answer, but most of them say one of two things: either they support a path to citizenship, or they support a path to some other kind of legal status, but not citizenship itself.

Interestingly enough, among the candidates who take the latter position — the more conservative one — are the son of a Cuban immigrant and the husband of a Mexican immigrant. Ted Cruz may be the farthest to the right (other than Trump) — he spends a lot of time decrying "amnesty" — but if pressed will say that he's open to some kind of restrictive work permit that would allow undocumented immigrants to stay in the country. Jeb Bush talks about a "path to legal status," but pointedly says that the path does not end in citizenship, but rather in something that resembles a green card, allowing the immigrant to work and live in the U.S., but not be an American citizen. (Bush used to support a path to citizenship, but not anymore.)

Others have taken the same position. Carly Fiorina says that some legal status might be acceptable, but not citizenship. Rick Santorum not only opposes a path to citizenship, but wants to drastically curtail legal immigration as well. Chris Christie used to support a path to citizenship, but has since changed his mind. Rick Perry is also opposed to a path to citizenship, but doesn't seem to have answered a specific question about the undocumented in some time.

Whenever any of them describes their path, whether to citizenship or some kind of guest worker status, it contains some key features. It winds over many years, involves paying fines and any back taxes, and also involves proving that the immigrant speaks English. The truth is that this last provision is completely unnecessary — this wave of immigrants is learning English no slower than previous waves did — but it's actually an important way for voters with complex feelings about immigration to feel less threatened and be reassured that the immigrants will become American.

For most of the candidates, the end of the long process is indeed citizenship. Scott Walker, after a bunch of incoherent and seemingly contradictory statements, finally said that he could eventually foresee a path to citizenship, once the border is secure (more on that in a moment). Marco Rubio will describe for you an intricate process that ends in citizenship, even if he seems reluctant to say so (Rubio was essentially cast out of the Tea Party temple after he proposed a comprehensive reform bill, which he has since dropped). Rand Paul has essentially the same position — he describes a path to citizenship, but doesn't like using the word. Bobby Jindal also supports a path to citizenship, as does Mike Huckabee, and John Kasich, and George Pataki, and Lindsey Graham, who has even said that he would veto any immigration reform bill that didn't contain a path to citizenship for the undocumented. Ben Carson has been vague on the subject, and as far as I can tell no one has asked Jim Gilmore.

But don't get the idea that any of these candidates are all that eager to move undocumented immigrants down that path too quickly. All of them say we need to "secure the border" before we even begin talking about how undocumented immigrants might eventually become citizens. And they seldom elaborate on what "securing" the border would mean. Would it mean not a single person could sneak over? If not, then what? In practice, they could always say that we can't get started on laying that path to citizenship because the border is not yet secure.

What all this makes clear is that you have to pay very close attention to understand what most of the candidates actually want to do, and even then you might not be completely sure. And even if there are plenty of Republican voters who would like to see a path to citizenship, at this point their voices are far quieter than the ones complaining about the invading horde. So if a Republican gets elected next fall, I wouldn't expect him to be in too much of a hurry to create a way for undocumented immigrants to eventually become Americans under the law.