UPDATED 8:15 PM EST -- A group of Democratic and Republican senators have reached a deal on how to handle future flows of lesser-skilled immigrant workers, with the approval of leaders from business groups and labor unions.
The agreement greatly improves the chances of passing an immigration reform bill since it comes with the support of two major interest groups, the AFL-CIO and the U.S. Chamber of Commerce, and resolves an issue that has long been a divisive element of immigration reform.
"This issue has always been the dealbreaker on immigration reform, but not this time," Sen. Chuck Schumer (N.Y.), the lead Democratic negotiator in the bipartisan Senate "Gang of Eight" working on the immigration bill, said in a statement Saturday night.
According to the AFL-CIO, the two sides have agreed on a new bureau called the "Bureau of Immigration and Labor Market Research," which would housed in U.S. Citizenship and Immigration Services and would be responsible for determining the number of visas based on labor shortages, unemployment, and the impact of immigration on labor markets.
The two groups have also agreed to a new visa program, the "W Visa Program," which would begin in April 2015. That program would allow employers to petition for lesser-skilled foreign workers for non-seasonal, non-agricultural jobs such as retail, janitorial, and construction jobs. The visa would not be temporary, workers would not be tied to a single employer and they would be allowed to petition for permanent status after one year. The visa cap would vary depending on the number of job openings and several other factors, but it would never be lower than 20,000 per year and never higher than 200,000 per year.
A representative for the Chamber did not immediately respond to a request for comment regarding the details of the plan. A senior Democratic aide told ABC News the deal was reached last night, but that senators must now complete work on the rest of the bill.
"Senate negotiators are making good progress on immigration reform, but we're not done yet," Alex Conant, a spokesman for Sen. Marco Rubio (Fla.), a Republican immigration negotiator, tweeted on Saturday.
"We expect that this new program, which benefits not just business, but everyone, will promote long overdue reforms by raising the bar for existing programs," AFL-CIO President Richard Trumka said in a statement. "But a new visa program is only a small part of our campaign to build a common sense immigration system."
Schumer informed White House chief of staff Denis McDonough on Saturday that the deal on low-skilled workers had been reached, congressional and White House sources told ABC News.
The deal represents a major breakthrough for the immigration reform effort and gives the process a positive boost of momentum. How to address low-skilled immigrant visas emerged as one of the biggest points of contention in the negotiations.
Business and labor groups had agreed to a set of broad principles on low-skilled visa program in February. But over the past month, they openly sparred over the details of such a plan, including contentious issues like wage levels for workers and which industries could use the visas.
The impasse in negotiations helped cause the "Gang of Eight" to miss a self-imposed March deadline to introduce an immigration bill, and threatened to further hold up the legislation, which is one of President Obama's top second-term priorities.
Other parts of the deal must be finalized, but the low-skill visa agreement indicates that senators will likely be able to roll out the bill when Congress returns from Easter recess after next week.
Over the past several weeks, business and labor have battled in the press over some of the finer points of the visa program. As recently as Friday, the two sides were still in a tug-of-war over what incoming workers should be paid.
Republicans began to point their fingers at labor unions, who initially balked an at expansive low-skilled immigrant worker visa program. The AFL-CIO's decision to not support a different type of guest-worker program in 2007 played a contributing role in the breakdown of that effort.
"I don't think it's any secret that in the past, unions killed immigration reform," Sen. Marco Rubio told Politico. "I think because of pressure from some of their members, they've at least publicly changed their stance on this. But I don't think they are doing cartwheels over this."
Labor unions laid blame for the stalemate at the feet of Republicans.
"We have conceded on so many different grounds. [Republicans] want to pave the path to citizenship with poverty," AFL-CIO spokesman Jeff Hauser told Reuters this week.
The AFL-CIO has stressed its commitment to immigration reform and a path to citizenship for undocumented immigrants. But last week, Ana Avendaño, a top immigration policy aide at AFL-CIO, said that accounting for the future flow of lesser-skilled immigrant workers "is arguably really not necessary to be in the package."
"Programs like the bracero program or temporary guest-worker programs where individuals were tied to an employer, they got exploited," the AFL-CIO's Trumka told Univision earlier this month.
But senators working out the deal have long said that a low-skilled worker program is an essential part of reform, underscoring the importance of the latest agreement.
"We recognize that to prevent future waves of illegal immigration a humane and effective system needs to be created for these immigrant workers to enter the country and find employment without seeking the aid of human traffickers or drug cartels," reads the "Gang of Eight's initial immigration framework.
ABC News correspondent Jeff Zeleny and Emily DeRuy contributed to this report.