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President Obama, just days into his second term, is pressing ahead on the explosive issue of immigration reform -- boosted Monday by a bipartisan group of senators drafting a proposal of their own while running into early criticism that the blueprint amounts to "amnesty."

The president is traveling Tuesday to Las Vegas, where he will outline his immigration reform goals, said to be similar to those he championed during the campaign. The issue was put on the back burner during his first term -- overtaken by debate over health care legislation and economic measures. But along with gun control, it is one of the top items on his second-term domestic agenda.

Eight U.S. senators got ahead of him Monday, unveiling a blueprint that calls for, among other things, a path to citizenship for the 11 million illegal immigrants already in the United States.

But White House Press Secretary Jay Carney said the president "welcomes" the proposal, saying it represents the "bipartisan support coalescing" behind certain principles of immigration reform.

"This is an important first step. ... We need to continue the movement," Carney said.

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An Obama administration official tells Fox News the senators' plan is on a trajectory that mirrors Obama’s immigration plan almost exactly, and that the White House is willing to let the group take the lead.

The aide says requiring illegal immigrants to pay back taxes and a fine and ensuring they would be at the back of the line after would-be legal immigrants have always been part of the president's immigration proposal. The president has also advocated for a path to citizenship.

Sen. Chuck Schumer, D-N.Y., one of the eight senators  called the new proposal a "major breakthrough" and said he hopes to turn it into legislation by March -- with the goal of passing something out of the Senate "by late spring or summer."

Sen. John McCain, R-Ariz., standing beside him, claimed 2013 is the "best chance" lawmakers will have to tackle immigration for years.

Even so, the proposed pathway to citizenship for illegal immigrants drew immediate criticism from others on Capitol Hill.

"No one should be surprised that individuals who have supported amnesty in the past still support amnesty," Rep. Lamar Smith, R-Texas, said. "By granting amnesty, the Senate proposal actually compounds the problem by encouraging more illegal immigration."

The eight senators who unveiled the new principles are Democrats Schumer, Dick Durbin of Illinois, Robert Menendez of New Jersey and Michael Bennet of Colorado; and Republicans McCain, Lindsey Graham of South Carolina, Marco Rubio of Florida and Jeff Flake of Arizona.

According to documents released early Monday, the senators will call for accomplishing four main goals:

--Creating a path to citizenship for the estimated illegal immigrants already in the U.S., contingent upon securing the border and better tracking of people here on visas.

--Reforming the legal immigration system, including awarding green cards to immigrants who obtain advanced degrees in science, math, technology or engineering from an American university.

--Creating an effective employment verification system to ensure that employers do not hire illegal immigrants.

--Allowing more low-skill workers into the country and allowing employers to hire immigrants if they can demonstrate they couldn't recruit a U.S. citizen; and establishing an agricultural worker program.

The principles being released Monday are outlined on just over four pages, leaving plenty of details left to fill in.

A Senate aide tells Fox News the group's principles say important security triggers must be met before a pathway for citizenship is created for illegal immigrants. Even then, the principles explicitly state that illegal immigrants must go to the back of the line behind would-be legal immigrants, and they will not be eligible for federal benefits while in the temporary legal status.

The aide tells Fox News that although many of the details of the bill still need to be worked out, those involved are encouraged by their progress and the support of senior senators. Members of the group on Sunday said they are seeking to craft a one-step, all-encompassing bill based on the shared principles.

"We are committed to a comprehensive approach to immigration that we can live with," Durbin told "Fox News Sunday."

Citizenship has been a sticking point in previous efforts, particularly among Capitol Hill Republicans. However, they appear willing to accept the path to citizenship, in part, so long as the legislation also includes tighter border security.

Tennessee Republican Sen. Bob Corker told Fox News he is optimistic but "details matter."

"We're at the talking points stage," he said. "We need to get to the legislation."

McCain said more work is needed on the legislation.

"I'm quietly optimistic we can get it done," he told ABC's "This Week."

McCain, a key player in the 2007 effort on immigration reform, also acknowledged that Obama's overwhelming support among Hispanics in the November elections was a wakeup call to Republicans that they need to do more to reach out to that growing part of the population.

The group has been working since the November elections on the legislation and is expected to have a complete bill by March or April.

Several of these lawmakers have worked for years on the issue. McCain collaborated with the late Democratic Sen. Edward M. Kennedy on comprehensive immigration legislation pushed by then-President George W. Bush in 2007, only to see it collapse in the Senate when it couldn't get enough GOP support.

Fox News' Mike Emanuel and The Associated Press contributed to this report.