Florida GOP Sen. Marco Rubio, a potential 2016 presidential candidate, pressed ahead Sunday with his multi-step immigration-reform plan, amid criticism that conservative voters have forced him to backtrack on comprehensive reform.

“I didn’t get elected to watch national poll numbers,” the first-term Republican senator said on “Fox News Sunday.”

Rubio said Washington has to address the “root causes” of the immigration issue, which has now turned into a crisis situation with tens of thousands of unaccompanied Central American youths coming into the United States illegally along the country’s southern border.

He said those problems include a 2008 law intended to protect children from non-bordering countries against human trafficking and President Obama’s 2012 executive memo that defers deportation to young people brought illegally to the U.S.

Rubio pointed out that Honduran President Juan Orlando Hernández has said the ambiguities in U.S. law have resulted in human traffickers persuading families to hire them to deliver their children from their violent neighborhoods.

“It’s serving as a lure,” he said.

Rubio also defended his plan by saying it remains comprehensive but has to be executed in the only way it will now pass in Congress.

"We will never have the votes necessary to pass one bill," he told Fox.

Rubio vaulted onto the national political scene in 2010, as one of the Tea Party-backed Republicans elected to Congress that year in the GOP wave that also took control of the House.

His profile, as a child of Cuban immigrant parents, positioned him to become a leading Republican in helping pass the Senate’s 2013 bipartisan, comprehensive immigration reform bill.

However, conservatives rallied to criticize the plan as “amnesty” for the roughly 11 million illegal immigrants now living in the U.S., which has effectively killed such a plan in the GOP-led House and caused Rubio to drop in polls.

The Democratic National Committee responded immediately to Rubio's comments.

"Rubio said he hasn’t flip flopped on immigration and that immigration reform is a priority for him," the group said. "If that’s the case, he has a pretty strange way of showing it. First he supported comprehensive reform and helped draft a bipartisan bill in the Senate, then he back tracked his support for his own bill. ...If that’s not flip flopping, then what is?"