WASHINGTON — Key senators are developing plans that would make it harder for U.S. citizens to get green cards for relatives while easing the path for more high-skilled foreign workers, according to aides and advocates familiar with negotiations over the emerging immigration deal.

The plans — which would run counter to policies that have been in place for generations — are part of talks between a bipartisan group of eight senators, whose bill is expected to serve as the template for a comprehensive immigration deal between Congress and the White House.

The senators agree a limited number of people should be allowed into the country each year; the question is who those people should be. Currently, about two-thirds of legal immigrants are admitted for family reasons and 14 percent for employment, according to the Migration Policy Institute. The rest are humanitarian cases. Green cards are permanent resident visas and allow holders to eventually become citizens.

Republicans would prefer to admit greater numbers of high-skilled workers, who business leaders say are in short supply and who would provide an immediate economic benefit. Democrats generally favor giving priority to relatives of citizens and legal residents already in the country, saying they provide support networks that help families thrive.

As it stands, spouses and minor children of citizens are given top priority, followed by unmarried children older than 21 and, lastly, married adult children and siblings. The Senate proposal would eliminate the latter two categories altogether, which add up to about 90,000 visas a year. Those people could still apply for entry into the country but would need other qualifications, such as high-tech skills, to be approved for a green card.

Senators involved in the negotiations stress that no decision has been made. But Sen. Lindsey Graham, R-S.C., a leader in the talks, said Thursday, “We’re going to change fundamentally the immigration system,” including tighter limits on family visas.

“Green cards should be reserved for the nuclear family. Green cards are economic engines for the country,” he said.

He added: “Right now you (give) green cards to adult children, to grandparents. What I want to do is reserve green cards based on the economic needs of the country, and we’ll do something for families.”

The group of senators, which includes four Democrats and four Republicans, has said it will release a comprehensive bill in early April. The Obama administration has expressed support for the group’s general principles.

The proposed changes to the family system have angered immigration advocates, who warn the move could threaten the chances of a broader agreement on an overhaul.

“Eliminating these categories would produce only a small reduction in visas while creating greater hardship for thousands of U.S. citizens and their loved ones,” two dozen members of the House Asian Pacific American caucus wrote in a letter to the eight senators last week. “We oppose any efforts to further limit the definition of family.”

The family visa program has been largely overshadowed by public debate over a path to citizenship for the nation’s 11 million illegal immigrants and an expanded guest-worker program for foreigners. But potential changes to the family visa program, which has a waiting list of 4.3 million people, also will play a pivotal role in any agreement reached by Congress and the Obama administration.

In 2007, some Democrats and the Roman Catholic Church objected to provisions in a comprehensive immigration bill that would have drastically reduced the number of family visas. The issue was one of several key reasons the bill failed to advance through the Senate.

The issue has mobilized Hispanics and Asian Americans, who have been at the forefront of family immigration debates since the Chinese Exclusion Act of 1882, which imposed stiff restrictions on Chinese immigrants until its repeal in 1943.

The current waiting list includes an estimated 1.9 million people from Asian countries, including China, Vietnam, India and Bangladesh. The wait for processing visas from the Philippines — which has the most family applicants other than Mexico — extends more than two decades, the longest of any country.

“The point that we’ve been trying to communicate to the White House and House and Senate is, ‘Who are we to define what a nuclear family is?’ ” said Mee Moua, president of the Asian American Justice Center, which has made family reunification one of its priorities. “Who are we to determine that the definition of family ends with a mother, father and minor children?”

People familiar with the talks said some Democrats in the group have decided they need to compromise on family visas to persuade Republicans to give ground on citizenship for undocumented immigrants. Democrats also are pushing for improvements to the family system that would expedite the green-card process by raising the limit for a single country’s percentage of annual immigrants from 7 to 15 percent.

Aides to Sen. Robert Menendez, D-N.J., a member of the bipartisan working group who pushed hard to support family reunification in the 2007 debate, declined to comment.

In addition to Graham, the Senate group consists of Republicans John McCain and Jeff Flake, both of Arizona; and Marco Rubio of Florida; and Democrats Charles Schumer of New York; Menendez; Dick Durbin of Illinois and Michael Bennet of Colorado.

Material from The Associated Press is included in this report.