WASHINGTON — A working group of senators from both parties is nearing agreement on broad principles for overhauling the nation’s immigration laws, representing the most substantive bipartisan effort toward comprehensive legislation in years.

The six members have met quietly since the November election, most recently on Wednesday. Congressional aides stressed there is not yet final agreement, but they have eyed next Friday as a target date for a possible public announcement.

The talks mark the most in-depth negotiations involving members of both parties since a similar effort broke down in 2010 without producing a bill.

“We have basic agreement on many of the core principles,” Senate Majority Whip Richard Durbin, D-Ill., a member of the group, said this week. “Now we have to draft it. It takes time.”

“The group we’ve been meeting with — and it’s equal number of Democrats and Republicans — we’re real close,” added Sen. Charles Schumer, D-N.Y., another member of the group.

The accelerated pace signals that immigration reform is expected to be one of Congress’s highest priorities, and it comes as the White House prepares to launch its own public campaign on the issue.

President Obama will travel to Las Vegas on Tuesday to speak about the need to “fix the broken immigration system this year,” the administration announced, an appearance in a state with a rapidly growing number of Hispanic voters, who overwhelmingly supported his reelection. Obama also met with members of the Congressional Hispanic Caucus on Friday.

“The president has made clear that he intends to act very quickly,” White House press secretary Jay Carney said Thursday. “I’m not going to hem him in by putting a timetable on it, but I think you can expect him to be true to his word, which is to take up this issue very early in his second term.”

Past efforts begun amid similarly high hopes have sputtered. But members of both parties increasingly see changes to the nation’s troubled immigration system as an area most likely to draw bipartisan agreement at a time when Congress is deeply divided on gun control, spending and taxes.

The optimism is spurred by the sense that the political dynamics have shifted markedly since the last two significant bipartisan efforts failed. In 2007, a bill crafted in the Senate died after failing to win support of 60 members despite backing from then-president George W. Bush. Many Republicans, and some centrist Democrats, opposed that effort because it offered a path to citizenship for illegal immigrants.

In 2010, extended negotiations between Schumer and Sen. Lindsey Graham, R-S.C., broke down without producing legislation.

Sen. John McCain, R-Ariz., a veteran of the 2007 effort who is part of the current working group, said Republican attitudes have dramatically shifted since the party’s defeat at the polls in November. Obama won more than 70 percent of the vote among Latinos and Asians, and a growing number of GOP leaders believe action on immigration is necessary to expand the party’s appeal to minority groups.

“Obviously, it’s had a very distinct impression,” said McCain, who lost his own bid for the White House in 2008. “It’s time to move forward on this.”

But he added, “I don’t claim that it’s going to be easy.”

Also included in the new Senate group are Schumer, who chairs the key Senate subcommittee where legislative action will begin; Graham; Robert Menendez, D-N.J.; and Marco Rubio, R-Fla.. Two others, Jeff Flake, R-Ariz. and Michael Bennet, D-Colo., have also been involved in some talks.

Their timetable would aim for a bill to be written by March or April and potentially considered for final passage in the Senate as early as the summer. Proponents believe adoption in the GOP-held House would be made easier with a strong bipartisan vote in the Senate.

The working group’s principles would address stricter border control, better employer verification of workers’ immigration status, new visas for temporary agriculture workers and expanding the number of visas available for skilled engineers. They would also include a call to help young people who were brought to the country illegally as children by their parents become citizens and to normalize the status of the nation’s 11 million illegal immigrants.

But obstacles abound. For instance, Rubio has said he believes immigrants who came to the country illegally should be able to earn a work permit. But he has said they should be required to seek citizenship through existing avenues, and only after those who have come to the country legally.

Democrats and immigration advocates fear that approach could result in wait-times stretching for decades, creating a class of permanent legal residents for whom the benefits of citizenship appear unattainable. They have pushed to create new pathways to citizenship specifically available to those who achieve legal residency as part a reform effort.

It is not yet clear if the Senate group will endorse a mechanism allowing such people to eventually become citizens — something Obama is expected to champion. Schumer said it would be “relatively detailed,” but would not “get down into the weeds.”

A source close to Rubio said he joined the group in December at the request of other members only after they agreed their effort would line up with his own principles for reform, which he outlined in an interview with the Wall Street Journal three weeks ago.

His ideas have since been embraced by conservatives, including some longtime foes of providing legal status to those who have come to the country illegally.

As a possible 2016 presidential contender widely trusted on the right, Rubio’s support could be key to moving the bipartisan effort.

And while Rubio and other Republicans have said they would prefer to split up a comprehensive immigration proposal into smaller bills that would be voted on separately, the White House will pursue comprehensive legislation that seeks to reform the process in a single bill.

“I doubt if there will be a macro, comprehensive bill,” said Sen. Johnny Isakson, R-Ga., who supported the 2007 effort. “Anytime a bill’s more than 500 pages, people start getting suspicious. If it’s 2,000 pages, they go berserk.”

But in an op-ed in the Wall Street Journal on Friday, Republican Jeb Bush, the former Florida governor, strongly supports a single comprehensive bill, writing that “Congress should avoid quick fixes.”

Schumer said Friday that a single package will be key for passage. “We’ll not get it done in pieces,” he said. “Every time you do a piece, everyone says what about my piece and you get more people opposing it.”

White House officials said they welcome the bipartisan Senate group’s deliberations and do not think it will conflict with the administration’s strategy. Some Democrats in the House, including Rep. Luis V. Gutierrez, D-Ill., have cautioned that the White House could harm the bid for bipartisan support if it acts too aggressively by authoring its own legislative proposal.

But advocates, who were disappointed that Obama did not follow through on comprehensive reform in his first term, said they expect the president to be out front on the issue.

“The president needs to lead, and then the Republicans have a choice: Are they going to do what they did in the last term and just be obstructionists?” said Eliseo Medina, secretary-treasurer of the Service Employees International Union, which spent millions recruiting new Hispanic voters this year. “Well, that didn’t work too well in November. Do the Republicans want the president not to get the credit? The best way to share the credit is for them to step up and engage and act together with the president. But it’s their choice.”

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