Republican presidential candidate Marco Rubio speaks to a voter at a town hall meeting at Kent Corporation headquarters in Muscatine, Iowa. Rubio has stayed vague on some issues in an apparent effort to navigate the primary and general elections. (Melina Mara/The Washington Post)

State Rep. Rio Tilton is “99.9” percent certain he’s going to vote for Marco Rubio. He’s far less sure where Rubio stands on abortion.

Does Rubio, like Tilton, 19, oppose abortions but favor exceptions, such as when a pregnancy results from rape?

“I should hope so,” Tilton said after braving the cold late last month to see the Florida senator campaign in a barn here. “I don’t know, exactly.”

After contemplating it, he added: “Now I’m going to think about looking into that.”

Rubio opposes abortion. But he has supported legislation with and without rape and incest exceptions, putting him on both sides of a heated sub-debate. His oft-stated goal is broad: reduce the number of abortions.

Sen. Marco Rubio (R-Fla.) greets supporters at the Growth and Opportunity Party in Des Moines in October. Many of Rubio’s own supporters are unclear where he stands on key issues. (Charles Ommanney/The Washington Post)

It is a habit with Rubio, a candidate aiming at moderate and conservative voters who often seems to advocate two positions at once. He tells voters that he has a personal view on the subject — whether abortion, immigration, Syrian refugees or gay marriage. But he also has a view of what is politically possible. Which, usually, is not what he personally wants.

That tactic allows Rubio to offer two right answers to the same question, and lets him carve out wiggle room on topics where none seemed possible.

He did it Tuesday night in Las Vegas, talking about immigration in the fifth Republican debate.

“I am personally open — after all that has happened and after 10 years in that probationary status where all they have is a permit — I personally am open to allowing people to apply for a green card,” Rubio said, talking about his views on whether and how to offer legal status to immigrants who entered the country illegally. Then the caveat: He is also open to not following his own personal views. If that’s what people want.

“That may not be a majority position in my party, but that’s down the road,” Rubio said. “You can’t even begin that process until you prove to people” that border security is working, he said.

Such a strategy might guard him against being pushed too far to the right for general election appeal, but avoid riling conservatives during the primaries. But the extent of his equivocation on key issues has left many Republicans, including his supporters, wondering what he really believes.

Republican presidential candidate Marco Rubio released a television advertisement on the eve of the final GOP debate of 2015. (YouTube/Marco Rubio)

At a meet-and-greet in an Oskaloosa, Iowa, coffee shop last month on the morning after a heavy snowfall, Rubio supporter Scott Szlachta told the senator that he drove from Chicago to ask him about H-1B visas, which are issued to high-skilled foreign workers and are championed by technology companies. Rubio co-sponsored a bill this year that would triple the annual cap on the number of H-1B visas issued.

“U.S. citizens that are in my spot — middle-aged computer science and electrical engineer workers in this country — have been horribly abused by the H-1B program,” he told Rubio.

Rubio sought to ease his concerns. He talked of reforms to ensure that companies are first trying to hire American workers for positions being filled by H-1B visa holders and to “close loopholes” to prevent a small group of “outsourcing” companies from dominating the visas.

But Rubio only briefly explained the general utility of increasing the number of H-1B visas, citing Canada’s efforts to lure American companies that want more hiring freedom.

Was Szlachta satisfied with Rubio’s response?

“To a point,” he said. “He sort of redirected.”

There has been confusion about Rubio’s position on immigration ever since he turned his back on a comprehensive reform bill he pushed in 2013 that included a path to citizenship for illegal immigrants.

“I don’t know exactly where he stands on that,” said undecided Republican voter Stephanie Hooton of Derry, N.H., before the barn event, a “No-B.S.” barbecue hosted by Scott Brown, the former U.S. senator from Massachusetts. “Some sort of amnesty, I think, is part of his plan.”

Rubio still favors a path to citizenship, which Democrats and moderate Republicans champion — but only after the border is secured and the legal immigration system is modernized.

Hooton’s main takeaway from Rubio’s immigration remarks was his stern warning that illegal immigrants convicted of crimes won’t be permitted to stay.

“I’m satisfied with his response regarding getting rid of the criminals,” Hooton said after Rubio spoke. “My biggest concern is getting rid of the criminals.”

While the major Democratic candidates for president have embraced a path to citizenship, there is far less agreement among Republicans. The divide poses challenges for Rubio, who is running as a candidate with broad appeal.

“I will work every day, not just to unify our party but to attract new people who haven’t voted for us in the past,” Rubio said here. “Not by changing my principles, but by convincing them that what we stand for is better than what the other side is offering.”

Asked in Iowa recently whether he would support Donald Trump if Trump is the GOP nominee, Rubio gave a roundabout answer.

“I’m going to support the Republican nominee. I believe the Republican nominee’s going to be someone that can win the general election. And I don’t believe Donald can,” Rubio said.

The disagreement over whether to allow Syrian refugees into the United States in the wake of the terrorist attacks in Paris last month is another potential hazard Rubio is navigating carefully.

Before the Paris attacks, Rubio seemed hopeful that the United States could accept more refugees fleeing chaos and war in Syria.

“We’ve always been a country that’s been willing to accept people that have been displaced. And I would be open to that, if it can be done in a way that allows us to ensure that among them are not infiltrated people who are part of a terrorist organization that are using this crisis,” Rubio said on Boston Herald Radio in early September. “I think, overwhelmingly, the vast and overwhelming majority of people that are seeking refuge are not terrorists, of course. But you always are concerned about that.”

But two days after the attacks, Rubio’s rhetoric had changed. Where the background check for Syrian refugees had previously seemed like an obstacle that could be overcome, now it seemed like an impossible task.

“You can’t pick up the phone and call Syria, and that’s one of the reasons why I’ve said we won’t be able to take more refugees. It’s not that we don’t want to, it’s that we can’t,” Rubio said on ABC’s “This Week With George Stephanopoulos.” “Because there’s no way to background-check someone that’s coming from Syria. Who do you call?”

A week later, however, Rubio said he was open to some refugees from Syria, in cases where “common sense” made clear that the refugee was not a security risk. He repeated his position at a town hall in Laconia, N.H., on the same day as the barn event.

“If you’re a 7-year-old orphan, if you’re a well-known Chaldean priest from the Middle East, if you’re a 90-year-old widow . . . these are people who can probably be easily vetted,” he said.

On social issues, Rubio has also walked a fine line. He drew widespread criticism from Democrats — and praise from conservatives — after underscoring at the first televised debate that he has never advocated allowing abortions in cases where a pregnancy is the result of rape or incest.

Although Rubio personally opposes abortions in all cases except to save the life of the mother, he does not always reject legislation containing other exceptions. Rubio’s explanation is that he will support a measure that he believes would lower the overall number of abortions performed.

Rubio personally opposes same-sex marriage, but — after a Supreme Court ruling made it legal nationwide — he urged conservatives to obey the decision. “The decision is what it is, and that’s what we’ll live under,” he said in July.

But in late November, Rubio seemed to urge the opposite tactic in a speech to conservative pastors in Iowa and in an interview with the Christian Broadcasting Network. If the law conflicts with God’s orders, Rubio said, Christians must ignore the law.

“We are clearly called in the Bible to adhere to our civil authorities. But that conflicts with also a requirement to adhere to God’s rules. And so, when those two come in conflict, God’s rules always win,” Rubio said in a video posted by CBN.

In the same interview, however, Rubio seemed to offer a caveat that negated what he had just said. He suggested that Christians could ignore the law only if they didn’t have the ability to change it through the democratic process.

“If you live in a society where the government creates an avenue and a way for you to peacefully change the law, then you are called to participate in that process, to try to change it. Not ignoring it, but trying to change the law,” he told CBN.

So: American Christians could ignore the U.S. Supreme Court ruling — but not if they live in the United States. It was a message that left one Coralville, Iowa, pastor puzzled about what Rubio actually believed.

“It did sound like he was, you know, talking out of both sides of his mouth,” said Brad Sherman, pastor of Coralville’s Solid Rock Christian Church and a supporter of former Arkansas governor Mike Huckabee’s campaign.

“These guys know how to use words,” said Sherman, speaking of politicians, “and leave themselves a little wiggle room in what they said. You’ve really got to hold their feet to the fire.”

Fahrenthold reported from Washington.