For millions of immigrants living in the US, the chance to vote against Donald Trump in November — who's distinguished himself in how casually he attacks immigrants of all varieties — becoming a citizen in time to vote seems like a potentially huge upside to going through the process.

Groups that work to register immigrants to start this process have been in a flurry of activity the past few months trying to get immigrants to naturalize, before the window closes for them to become citizens in time for Election Day. They talked up a huge surge of new applications. And a Democratic win for the White House could depend on it.

But is the surge for real? Unfortunately, we just don't have the hard data yet — and there is evidence to suggest that interest these groups see in becoming a US citizen doesn't necessarily translate to going through the steps to send in the application.

Getting immigrants to naturalize is a key part of Democrats' 2016 strategy

Democrats need the electorate to look more like it did in 2008 and 2012, when it elected and reelected Barack Obama, than it did in 2010 and 2014, when it gave Republicans majorities in the House and Senate (respectively). That means more voters, more young voters, and — crucially — more nonwhite voters, especially Latinos.

It's easier to mobilize Latino voters if there are more of them to mobilize. And there's a huge untapped population of Latinos who aren't yet on the voter rolls but could get there with a little effort: both Latino citizens who aren't registered voters and Latinos who are eligible to become citizens but haven't yet naturalized.

The latter group is a lot bigger than you might think.

There are about 8.8 million people in the US who are eligible to naturalize. Compared with that, the 650,000 people who became citizens in 2014 looks pitiful — a mere 7 percent.

Latinos, particularly Mexican Americans, are overrepresented among immigrants who can but haven't become citizens. Data tells us that 30 percent of the citizenship-eligible population was born in Mexico, while only 17 percent of the people who became citizens in 2014 were born there. Even when they do become citizens, they tend to wait longer than immigrants from elsewhere: New citizens born in North America have typically had green cards for 10 years or more, a couple of years longer than immigrants from other parts of the world.

The advocacy groups leading the naturalization push this spring take the position that this is a moral issue — both because citizenship is important in its own right and because it's important to have an electorate that looks as much like America as possible.

Naturalization rates always go up in presidential election years, as immigrants are presented with an obvious, tangible reason to become citizens. Groups like the ones involved in the Stand Up to Hate campaign, which expressly targets immigrants who want to vote against Trump, want to turbocharge the usual quadrennial trend. But when it comes to the practicalities of how to do that, things get tricky.

There are two ways of looking at the could-be-voter population. One is that it represents millions of voters' worth of low-hanging fruit for Democrats and voter mobilization groups, if only they can organize and get the word out. The other is that it is harder for Latino immigrants to become citizens than it is for immigrants from elsewhere — because they're less fluent in English, don't have the money to pay application fees, etc.

How effective a naturalization push can be depends a lot on which one of those is the case.

And the naturalization window is closing. There's no official deadline to file a citizenship application before Election Day, because the government doesn't make any guarantees about processing time — but right now it takes about six months (give or take some regional variation) from application to naturalization.

That basically means that an immigrant who hasn't submitted an application by mid-May is cutting it very close, and one who doesn't submit by the end of May is quite possibly out of luck.

How genuine is the upswell against Trump?

Over the past few months, a lot of newspapers and magazines have run articles along the lines of (per the New York Times's entry in the genre) "More Latinos Seek Citizenship to Vote Against Trump."

But there's a bit of a chicken-and-egg problem here. The implication of headlines like that is there's been an organic groundswell of interest among Latinos in finally becoming citizens, because they see Donald Trump on their television screens and want to make sure he doesn't become president.

"There's something new going on," Rep. Luis Gutierrez (D-IL) told reporters on a press call Wednesday. "And I think we all know that it has something to do with the tenor or tone of the presidential race. It's frankly scaring people into coming forward, and going through with the citizenship process."

That might be true. It is definitely true that many Latinos took Trump seriously from the very beginning of his campaign, and were scared of what he was saying at a time when many political observers thought he was a joke. And there are plenty of reports of lines out the door at citizenship clinics in Los Angeles, Denver, and Chicago.

But it's hard to marshal data to demonstrate that people registering so they can vote against Trump is a genuine phenomenon — something big enough to change the electorate — instead of an anecdotal trend. (There's also the possibility that Trump is driving immigrants to naturalize for another reason; I've heard reports that some immigrants are becoming citizens as a protection against deportation, since even green card holders can be deported over somewhat minor crimes.)

But if the hype doesn't translate into large numbers of new eligible voters, it doesn't actually change the prospects of keeping Trump out of office. In fact, if the resources being poured into naturalization don't generate big results, it bodes poorly for the effectiveness of voter registration and get-out-the-vote efforts down the line.

The signs are good, but it's still too early to tell

From October to December 2015, naturalization applications were up about 14 percent from the year before. That's okay, but not great: The goal of the advocacy groups, to get 1 million of the 8.8 million eligible immigrants to naturalize, would require about a 35 percent increase.

But the seasonal pattern of applications for citizenship makes it clear how hard it is to generalize from winter of one year to spring of the next:

Anecdotally, nearly everyone I've talked to — not only in the community groups that help put applications together but in the federal government — confirms that there really has been an uptick in citizenship applications this spring. But without firm data, it's hard to figure out how much is hype.

The Stand Up to Hate campaign, which encompasses many of the leading advocacy groups working on naturalization, made contact with more than 500,000 people via social media, phone, or email. They held 300 events. And at the end of the day, as of the end of April, they filled out 12,781 applications for citizenship.

If none of those immigrants would otherwise have applied for citizenship, that would represent a 9 percent increase from March and April of last year — which was a relatively weak spring for applications, as the graph above shows. And of course, some number of those immigrants would have applied even without the big campaign push.

But whether the excitement and media buzz generated by the campaign actually spurred thousands of immigrants to submit their own citizenship applications is up for debate. We'll know that in the coming months. We don't know it quite yet.

The wild card: fee shifts

As powerful a motivation as presidential elections are for eligible citizens, there's actually one thing that can be an even bigger factor in spurring them to naturalize: changes to application fees. Sarang Sekhavat, the federal policy director for the Massachusetts Immigrant and Refugee Advocacy Coalition, estimated off the cuff that his group has processed a fairly typical number of applications for an election year — but not as many as in 2007, when an announced fee increase led thousands of immigrants to get their applications in before the increase took effect.

Last week, the federal government announced that starting on October 1, 2016 (the first day of fiscal year 2017), the base cost of filing a naturalization application will go up slightly, from $595 to $640.

For many immigrants, though, the cost will go down in practice. In addition to having a full waiver for certain immigrants based on military service economic need, the government is allowing more immigrants to pay a lower price. Immigrants who make less than 200 percent of the federal poverty level will only have to pay $320 for a citizenship application. That covers an estimated 1 million of the 8.8 million eligible immigrants.

The changes will take effect far too late to affect who'll be eligible to vote in November. And they were announced too late to affect the calculus of most of the immigrants who did apply in time.

But they could encourage some immigrants who have been struggling to save up enough to get in an application before the end of May to simply hold off until fall. Conversely, the increase in the application fee for more affluent immigrants (while slight) could be enough to give them the extra nudge to file an application that's been sitting on a desk half-completed for months.

Getting people to naturalize isn't the same as getting them to vote

As hard as it is to translate interest in citizenship into filing an application, it's even harder to bring new citizens to the polls. Naturalized citizens still have to register to vote, and registered voters still have to be mobilized to actually do it.

Latinos lag in both of those cases. In 2012, only 41 percent of eligible Latino voters were registered. Fewer than half of Latino eligible voters actually voted (compared with rates above 60 percent for both white and black Americans).

Many local advocacy groups have started handing out voter registration forms after naturalization ceremonies — in the hopes that the excitement of becoming a citizen will make people more enthusiastic about exercising the rights that come with it. But some groups I talked to are only beginning to put together an effort to track people from naturalization to registration to turnout, or even to integrate the efforts getting people to each step.

On a macro scale, getting eligible voters to vote is bigger than getting people to naturalize — there are simply more of them, and there isn't a six-month lag time or a $600 fee to present bumps in the road. But as with naturalization efforts, there are some structural barriers, and it's not yet clear that more money, more organizations, and more buzz is enough to surmount them.

This is why the naturalization push is such an important barometer. If it turns out that the anecdotes are true, and the surge is real, it will be a show of how powerful the Latino voter mobilization machine will be in 2016. If not, it's just an interesting trend story in the Year of Trump.