PHOENIX (AP) — Reyna Montoya was 10 when she and her family fled violence in Tijuana and illegally immigrated to the U.S. Growing up in Arizona, she worried even a minor traffic violation could lead to her deportation.

She didn’t feel relief until 11 years later in 2012, when she received a letter confirming she had been accepted to a new program for immigrants who came to the country illegally as children.

“All of the sudden, all these possibilities opened up,” Montoya said, fighting back tears. The Obama-era Deferred Action for Childhood Arrivals program granted her and hundreds of thousands of others two-year, renewable permits to live and work in the U.S. legally.

But as President-elect Donald Trump prepares to return to the White House, after an unsuccessful bid to end DACA in his first term, the roughly 535,000 current recipients are bracing yet again for a whirlwind of uncertainty. Meanwhile, a years-long challenge to DACA could ultimately render it illegal, leaving people like Montoya without a shield from deportation.

“I have to take his (Trump’s) words very seriously, that when they say ‘mass deportation,’ it also includes people like me,” said Montoya, who runs Aliento, an Arizona-based advocacy organization for immigrant rights.

Uncertainty is nothing new for DACA recipients. As many matured from school age to adulthood, they have witnessed a barrage of legal threats to the program.

DACA hasn’t accepted new applicants since 2021, when a federal judge deemed it illegal and ordered that new applications not be processed, though current recipients could still renew their permits. The Biden administration appealed the ruling, and the case is currently pending.