U.S. Sen. Marco Rubio raised more money in the first quarter of 2013 than in all of 2012, according to published reports.

The Republican junior senator from Florida raised $2.3 million from 15,000 donors nationwide.

The potent fundraising further brightened the 2016 presidential glow around Rubio, who has commanded headlines in the last two weeks for his pivotal role in the Senate immigration bill to be unveiled this week.

Many have seen his taking a central role in the highly charged immigration debate as a gamble. Though Rubio is part of the so-called “Gang of Eight,” made up of four Democrats and four Republicans, but it he who has attracted the most attention in discussions about their proposed bill.

The new fundraising figures suggest that thus far, his role in the limelight has not hurt, and perhaps even enhanced his image as a leader, political experts say.

Those who want more liberal immigration rules disagree with Rubio’s insistence, in a bow to the more conservative members of Congress, on tighter border security being a key part of any reform measure.

Advocates of more lenient treatment of undocumented immigrants also have criticized the long wait, more than a decade, that those here illegally would have to wait to obtain legal permanent residency, more commonly known as a "green card."

But those who want stricter immigration laws have expressed disappointment with Rubio, taking issue with his support for allowing undocumented immigrants to work and live here legally – with a provisional legal status – while they wait to be eligible to apply for permanent residency.

Those opponents see it as “amnesty.”

“When the Gang of Eight was first formed a publicly stated principle was the enforcement would come first—before legalization,” said U.S. Sen. Jeff Sessions, an Alabama Republican and a senior member of the Senate Judiciary Committee. “[The] Gang of Eight members admitted that they abandoned this principle and that, in fact, legalization—or amnesty—would come first. This proposal offers immediate legalization with unfulfilled promises of enforcement in the future.”

On Sunday, Rubio made the rounds of Sunday television shows to push the Senate bill.

"This is not 'amnesty,” he said on “Fox News Sunday.” "'Amnesty' is the forgiveness of something. 'Amnesty' is anything that says 'do it illegally, it'll be cheaper and easier.’”

He stressed that the bill would require undocumented immigrants to pay penalties, back taxes and meet a strict set of criteria before they would be considered eligible for citizenship.

Many, including Democrats, have lauded Rubio for helping to make the immigration reform process more likely to lead to a bill that could gain passage in Congress.

And public opinion polls have showed that a majority of Americans support a path to citizenship.

On Sunday, Rubio shrugged off suggestions that he has the 2016 presidential race on his mind.

"I have a job," Rubio said in a CNN interview. "My belief has been if I do my job and I do my job well, I'll have options and opportunities in the future to do things whether it's run for re-election, run for something else or give someone else a chance at public service. And that's how I view this issue."

Elizabeth Llorente can be reached elizabeth.llorente@foxnewslatino.com

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