Florida Sen. Marco Rubio, along with seven Republican and Democratic colleagues Monday, released what they called a “tough but fair” immigration-reform plan to tighten border security, increase guest-worker permits and give a pathway to citizenship for millions of those who are unlawfully in the country.

The five-page plan from the bipartisan “Gang of Eight” contains most of the key concepts Rubio touted over the past month, winning support from conservative commentators. The senators, still working on the ever-important specifics, want to draft legislation by March and vote on it by August.

The most-controversial proposal: giving a pathway to residency — and even citizenship — to many of the estimated 11 million immigrants unlawfully in the United States. An estimated 825,000 live in Florida.

While some conservatives call it amnesty, Rubio says it’s not because immigrants would be penalized. They would have to pay fines, back taxes and undergo a criminal background check — a similar proposal made by President Barack Obama in May 2011.

“This is a big deal,” White House spokesman Jay Carney said Monday. “This is an important development.”

Rubio said lawmakers have little choice but to legalize the immigration status of those who came or remain here unlawfully.

“We can’t round up millions of people and deport them,” Rubio wrote Sunday in the Las Vegas Review Journal, the home newspaper of Democratic Senate leader Harry Reid.

“But we also can’t fix our broken immigration system if we provide incentives for people to come here illegally — precisely the signal a blanket amnesty would send,” Rubio wrote.

Those undocumented immigrants allowed to stay would remain under a “probationary legal status” for an as-yet-undetermined period. They wouldn’t have access to welfare during that time. Nor would they be eligible for a green-card until 1) those who followed the rules get their chance first and 2) The borders are verified as secure.

The border-security verification, according to the senators, would be made by “a commission composed of governors, attorneys general, and community leaders living along the Southwest border.” However, the commission’s findings might be only advisory.

Republican concerns about border security and amnesty helped scuttle a 2006-2007 immigration plan, which closely mirrors this proposal, said Arizona Sen. John McCain who unsuccessfully pushed for that legislation with the late Sen. Ted Kennedy. He said Republican resistance to immigration reform has kept Hispanics away from the GOP.

Since 2007, popular support for immigration reform has grown, said Sen. Charles Schumer, D-N.Y. A new national FOX News poll found that 56 percent of Republicans, 69 percent of independents and 74 percent of Democrats believe in a path to citizenship for the undocumented.

“For the first time ever, there’s more political risk in opposing immigration reform, than supporting it,” said Schumer, who cautioned that there are still “loads of pitfalls.”

Among the plan’s grab-bag of ideas: give special consideration to farm laborers, high-tech workers and young people who were brought illegally to the U.S. as children. The latter proposal has echoes of the DREAM Act for some college- and military-bound undocumented immigrants. Immigrants who receive “a PhD or Master’s degree in science, technology, engineering or math from an American university” could get a green card.