MIAMI — (CNN) The Cubans are coming — and the timing couldn’t be worse for Marco Rubio.

As the Florida senator tries to fend off attacks from left and right about his stance on immigration, about 8,000 Cuban migrants are making their way to the United States’ southern border, with the first dozens recently reaching the Texas border.

They’re hoping to benefit from a decades-old policy that allows Cubans to get U.S. residency when they set foot in the country. Their arrival will put the Cuban-American GOP presidential candidate squarely in the spotlight, caught between a party looking for a hardline stance on immigration and a community calling him a “traitor” and flip-flopper.

“With all this talk about walls, national security and enforcing the border, this is a hell of a bad time for thousands of Cubans to be showing up at the border with Mexico with the expectation to get into the United States,” said Republican strategist, CNN commentator and Rubio friend Ana Navarro.

The political climate is ripe for the mass migration to crash the 2016 conversation. Immigration has been a central topic in the Republican primary, with front-runners like billionaire businessman Donald Trump and Texas Sen. Ted Cruz picking up large amounts of support for backing heavy border security and tough measures against illegal immigration.

Rubio has been a frequent target of their attacks. He’s caught in a bind between criticism from the GOP base on past efforts to reach a bipartisan deal on immigration reform — derided as “amnesty” by his opponents — and his desire to rally Hispanic support in a general election contest.

Cubans entering the U.S. have skyrocketed in the past year since President Barack Obama announced he would normalize relations with their homeland, with Cuban immigration jumping 78% over fiscal year 2014 and doubling from the period of January to March after his announcement, according to Pew Research Center In that three-month window, 9,900 Cubans entered the U.S.

Rumors that the United States could soon do away with its policy of letting Cuban immigrants stay in the U.S. and qualify for benefits if they make it here — unlike other Latin American immigrant groups — has spurred an arduous journey for thousands through Central America hoping to cross the Mexican border.

Though the Obama administration has denied any impending change to the policy, the Castro regime has long opposed it and Cubans fear Washington will scrap it as part of the rapprochement.

Immigration, meanwhile, has for years been a hot-button issue for both Democrats and Republicans, and the temperature has only increased during the 2016 race.

Trump’s rise to the top has come in part from advocating building a wall along the Mexican border, deporting undocumented immigrants and temporarily banning all Muslims from entering the United States.

Cruz, like Rubio a freshman senator and the child of a Cuban immigrant, has adopted policies only a tad less aggressive than Trump, mimicking his call for a wall with Mexico and running as a longtime border security hawk.

The positive response from the Republican grass roots has made it hard for Republicans who are moderate on immigration to gain traction. And the Cuban migration effort will make that dance even tougher for candidates, like former Florida Gov. Jeb Bush and Ohio Gov. John Kasich, who have tried to express empathy towards undocumented immigrants already living in the U.S.

But none of the candidates are likely to feel the glare of the spotlight like Rubio, who is Cuban-Amerian, having supported a path to citizenship in the past and running a campaign on how connected he is to the immigrant community. The fact that he also has a hefty lead over Bush and Kasich in the polls also ensures he’ll come under fire from competitors on the issue.

A super PAC supportive of Cruz has already released a brutal attack ad even before the Cuban issue has risen to the surface. It uses Rubio’s own words and the words’ of his Democratic allies to paint him as a flip-flopper who ultimately supports a pathway to citizenship for undocumented workers as evidenced by his participation in drafting bipartisan immigration reform — which he has since distanced himself from.

“His fingerprints are all over that bill,” New York Democratic Sen. Chuck Schumer says of Rubio in a 2015 interview clip.

The Florida senator is himself the child of Cuban immigrants, was the first Cuban-American speaker of the Florida Legislature and represents the biggest concentration of Cubans in the United States.

He is fond of calling attention to his background on the trail, saying his closeness to immigration gives him the best insight of any candidate.

“Of all the people running, no one understands it better than I do,” he said last Wednesday in South Carolina, pointing out that his and his wife’s parents and grandparents, like all his neighbors, were immigrants. “I understand this issue, the good, the bad, the ugly.”

His closeness with the Hispanic community is seen as an asset for the general election, given their growing vote, and Rubio’s history of moderation on immigration could help him peel votes from a Democrat like Hillary Clinton.

Given the blowback from some conservatives, Navarro said at this point in the campaign, Rubio should be “paying” for protesters to heckle him as harsh on immigration, as they did in Columbia, South Carolina, earlier this month, but Navarro said embracing that image too tightly could hurt his long-term general election prospects.

Rubio has chosen to pursue a harder line on immigration since announcing as a GOP candidate, and introduced legislation last week in the Senate that would roll back some benefits to Cubans unless they are legitimate political refugees.

He has also distanced himself from the comprehensive immigration reform he tried to get passed in 2013 along with Schumer and other senators in the so-called Gang of Eight. It would have created a path to citizenship for immigrants living in the U.S. illegally, but the bill died in the House.

Rubio has since said he no longer believes in comprehensive immigration reform and that the government must prove a commitment to enforcing its immigration laws before any attempt is made at reforming them.

And he has said that he would not welcome the migrants making their way to the U.S., calling it “unacceptable” for migrants to try to enter through Central America and the southern border.

“You’ve seen a huge upsurge now after the deal the President made with the Castro brothers, and it’s becoming a real crisis,” Rubio told reporters in New Hampshire two weeks ago, part of comments about the legislation from the 1960s that created the special allowance for Cuban migrants to stay in the U.S. and apply for benefits.

“We’re going to have to reexamine not just the Cuban Adjustment Act and make changes to it based on new realities but also the benefits people are qualifying for,” Rubio said.

Cuban-Americans hold a different view. In a December survey of 400 Cubans and Cuban-Americans conducted by Bendixen & Amandi International, 65% said Cubans stranded in Central America should be allowed to come to the United States, with less than 20% saying they should be sent back to Cuba.

Cubans in the U.S. are more split on whether to continue the Cuban Adjustment Act, but a minority support repealing it all together.

Rubio has long toed a careful line on Cuban immigration, hesitant to embrace preferential treatment and making special note in a 2011 Politico op-ed that while his parents came to the United States pre-Castro, they did so “legally on an immigration visa … not, as some have said before, as part of some special privilege reserved only for Cubans.”

But that line, along with his hardening stance during the GOP primary race, has antagonized the left. In South Carolina earlier this month, he was repeatedly interrupted by protesters, who accused him of being a traitor to the Hispanic community.

“He’s very much an immigrant traitor,” said Julieta Garibay, deputy advocacy director for United We Dream, a group that focuses on undocumented youth and was behind the protests. “He plays this card of, ‘I have an immigrant background and I’m proud of my parents,’ but yet he puts out this legislation that would definitely negatively impact folks coming from Cuba,” she continued.”It’s a disgrace.”

Cristóbal Alex, president of the Latino Victory Project, said Rubio cannot “unburn the bridge” that he cut with the Latino community when he backtracked on immigration reform.

“He really is caught between a rock and a hard place,” Alex said. “He could be just completely stuck in this uncomfortable area for him that doesn’t allow him to regain his footing with the Latino community (while) folks that are running for president on the Republican side will continue to go after him for.”

Rubio may still be able to find a way through the muddle. His approach so far has been to portray himself as the adult in the room.

“I was here a few days ago repeatedly heckled by this group … and I told them, ‘We’re going to enforce our immigration laws,'” Rubio told a crowd in South Carolina last Wednesday. “As the son and grandson of immigrants, I know for a fact that enforcing our immigration laws is not anti-immigrant, it’s what sovereign countries do.”

His bill to curtail abuses of benefits by Cubans has general support in the Cuban-American community and has been signed onto by other Cuban lawmakers from Florida.

“Marco is experienced and pretty good at navigating the waters where immigration and (the) Cuba debate intersect, and he is attuned to the pulse of the community in South Florida,” said Navarro, the political analyst.

Experts on the situation in Havana said Republicans — historically strong supporters of the Cuban-American community — could thread the needle and make a case to Americans that Cubans deserve a special provision of immigration policy not afforded to other migrant groups even as they pitch border security.

“Most of the candidates have been leaning to really tighten the borders, and then they’ll say, ‘Except for Cubans, because the Castros are still controlling the country, and Obama’s negotiating with dictators,'” said Ted Piccone, a senior fellow and Cuba expert with the Washington-based Brookings Institution. “It allows them to toe the line in a rational way.”

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