Republican Presidential candidate Marco Rubio (R-Fla.) participates in a roundtable discussion at Saint Anselm College in Manchester, N.H. (Darren Mccollester/Getty Images)

Marco Rubio committed Wednesday to ending President Obama’s controversial program for child immigrants even if Congress doesn’t create an acceptable alternative, hardening his opposition in the wake of criticism by presidential rival Donald Trump.

Rubio also said he would soon release years-old credit card records that have never been made public a day after Trump slammed his spending habits. The Rubio campaign had already intended to release the records before Trump’s comments.

As the senator from Florida ascends in the polls and builds support in the GOP, no other candidate has zeroed in on his vulnerabilities as much as Trump, whose freewheeling attacks have forced Rubio into a defensive posture as he tries to move up in the race.

Trump repeated his criticism Wednesday while visiting Concord, N.H., to formally file paperwork for New Hampshire’s first-in-the-nation primary. He called Rubio a “disaster on his finances” — a reference to his questionable use of a card issued by the Republican Party of Florida — and cast him as soft on immigration.

Here in Manchester, Rubio went further than he has before in demonstrating his commitment to ending Obama’s Deferred Action for Childhood Arrivals program, which is loathed by many conservatives.

Republican presidential candidate Donald Trump reacts after filing his declaration of candidacy to appear on the New Hampshire primary ballot in Concord, N.H. (Brian Snyder/Reuters)

“If you’re president and Congress doesn’t pass immigration reform, would you keep DACA going?” a reporter asked Rubio.

“No,” Rubio responded. “It will have to end at some point.”

“Even if the Congress doesn’t pass legislation?” the reporter followed up.

“Yes, it will have to end,” he replied.

DACA is an initiative unveiled by Obama in 2012 that granted temporary protection to hundreds of thousands of immigrants brought to the United States illegally as children.

Rubio had previously said the program would have to end eventually but left unclear whether he would end it without reforms. In an interview in the spring with Fusion’s Jorge Ramos, Rubio said he was not calling for DACA “to be revoked tomorrow or this week or right away” and said he hoped “it would end because of some reform to the immigration laws.”

A hard-line posture on immigration could help Rubio in the primaries, but it also poses a risk in a general election by dampening support among Latinos and other minority groups. Rubio’s shifts on the issue — he ­co-sponsored and then disavowed comprehensive immigration legislation in the Senate — is also providing fodder for opponents.

Presidential candidates Sen. Marco Rubio (R-Fla.) speaks while Donald Trump looks on during the CNBC Republican Presidential Debate in Boulder, Colo. (Justin Sullivan/Getty Images)

“Marco Rubio is about as trustworthy on immigration reform as he is on his tax plan and his personal finances,” Democratic National Committee spokesman Eric Walker said in a statement.

In addition to talking about immigration, Rubio also promised to release financial records that have never been disclosed publicly some time “in the next few weeks.” As a leader in the Florida House, he was issued an American Express card by the state GOP.

Rubio reimbursed the state party for flights he said were mistakenly billed to the party and also paid personal expenses that he had charged to the card.

Those expenses were scrutinized heavily by the Florida press during Rubio’s Senate campaign. But the public got only a partial picture because records from 2005 and 2006 have never been released.

Rubio defended his use of the card Wednesday and brushed off Trump’s attacks as old news.

“It’s been coming up for five years,” he said. “It wasn’t a credit card; it was a charge card. It was American Express. And every month I would get a bill in my home, and I would review it. And if it was something on it that was personal, I would pay it. And if it wasn’t, the party paid it.”

He said that if he could go back and change how he used the card, “I just wouldn’t have done any personal things on it because I would have avoided all that confusion it’s created in the minds of some.”

The remarks came during a question-and-answer session at Saint Anselm College organized by young professional groups. During the exchange, Rubio fielded some light questions, including which non-politician he would want have a beer with (Nobel Peace Prize winner Malala Yousafzai , among others), what kind of food he would serve at a party (“I like Tex-Mex”) and the “Star Wars” movies.

“I used to hate Darth Vader. Now I kind of feel a little bit sorry for him,” Rubio said, noting the villain started out with a “tremendous amount of talent and promise.”

Afterward, when the discussion with reporters turned to Trump, Rubio came prepared to lob a barb back at him.

“When Donald comes across a poll he doesn’t like, it gets weird and he does these sorts of strange things,” he said.