Saying their proposal would "secure the border, modernize and streamline our current legal immigration system" and create "a tough but fair legalization program for individuals who are currently here," eight senators unveiled a "bipartisan framework for comprehensive immigration reform."

The Associated Press writes that "although thorny details remain to be negotiated and success is far from certain, the development heralds the start of what could be the most significant effort in years toward overhauling the nation's inefficient patchwork of immigration laws."

Update at 3:07 p.m. ET.

During a press conference at Senate Radio-TV Gallery, five of the senators sounded downright upbeat about the set of "bipartisan principles" they hope will turn into legislation the Senate could consider in late spring or early summer.

Sen. John McCain, a Republican from Arizona, said he was "truly optimistic" that a comprehensive immigration reform law would be passed in 2013.

This is a "first step," said McCain. It's "difficult, but achievable."

Sen. Dick Durbin, a Democrat from Illinois, said that he felt "good about our chances this time." Twelve years ago, said Durbin, he introduced the first "Dream Act." This time around, he said, "the Dream Act will be an integral part of comprehensive reform."

Our Original Post Continues:

Politico says "the broad agreement by the influential Gang of Eight senators amounts to the most serious bipartisan effort to act on the highly charged issue since George W. Bush's comprehensive measure was defeated in the Senate in 2007."

It comes a day before President Obama is due to speak about his own proposals on immigration reform. As Politico adds, "it remains to be seen if Obama will embrace the Senate effort, or how closely his own proposal hews to the Senate one. But the Senate proposal is expected to take precedence on Capitol Hill, given that bipartisan backing will be crucial to getting anything through the Democratic-controlled Senate — let alone the Republican-controlled House."

One of the senators — Republican John McCain of Arizona — said Sunday on ABC-TV's This Week that "the time is right" for reform. "There is a new ... appreciation on both sides of the aisle, including maybe more importantly on the Republican side of the aisle, that we have to," McCain said.

The eight senators are:

-- Republicans McCain, Lindsey Graham (S.C.), Marco Rubio (Fla.) and Jeff Flake (Ariz.).

-- Democrats Charles Schumer (N.Y.), Richard Durbin (Ill.), Robert Menendez (N.J.) and Michael Bennet (Colo.).

According to The Washington Post, the senators' proposal would "allow undocumented immigrants with otherwise clean criminal records to quickly achieve probationary legal residency after paying a fine and back taxes. But they could pursue full citizenship — giving them the right to vote and access to government benefits — only after new measures are in place to prevent a future influx of illegal immigrants."

An estimated 11 million people across the nation do not have the documentation to prove they are in the country legally.

The Post has put a copy of the senators' proposal online here. In it, the senators also say their plan would continue to provide the Border Patrol "with the latest technology, infrastructure and personnel need to prevent, detect and apprehend every unauthorized entrant."

The Wall Street Journal notes that:

"The agreement provides a variety of other provisions. Among them: alleviating the backlog of people waiting to immigrate legally; awarding green cards to those who earn doctorates from U.S. universities in science, technology, engineering or math; stiff fines and possible criminal penalties for employers that fail to verify workers' legal status; and creation of a program to fill low-skilled jobs that employers cannot get Americans to take."

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