Amid the initial elation from immigration advocates over a new proposal to overhaul the nation’s border-control laws was a sense of unease over the 844-page bill’s core provision: a path to citizenship for immigrants in the country illegally.

Proponents of immigration reform have pushed for decades to allow undocumented immigrants to become legal residents and, ultimately, citizens. But advocates expressed concern Wednesday that the path created by an eight-member bipartisan Senate group is too onerous, expensive and uncertain.

The fear, the advocates said, is that hundreds of thousands, or even millions, of the estimated
11 million undocumented immigrants living in the United States will never have the chance to remain in the country legally.

Provisions in the bill could make it nearly impossible for “many immigrants to make it to the finish line and become citizens,” said Marielena Hincapié, executive director of the National Immigration Law Center.

The challenge facing advocates is to push lawmakers to find ways to amend the legislation to make the path to citizenship easier without upsetting the delicate political balance and potentially killing the deal.

President Obama has said he expects a “clear path” to citizenship. Administration officials said they will reserve judgment on the details until they have carefully examined the legislation.

Public debate over the proposal is expected to focus heavily on the citizenship component — long a non-starter among conservative Republicans, many of whom who remain fiercely opposed to granting what they call “amnesty” to the undocumented population.

GOP supporters of the immigration bill, including Sen. Marco Rubio (R-Fla.), say the proposal allows a path to legal status and citizenship only after rigorous new provisions are in place to enforce control of the border.

But Rubio already is taking heat from conservatives. On Tuesday, several dozen tea party activists demonstrated at some of the senator’s Florida offices, and conservative Web sites on Wednesday charged that the bill would distribute free “amnesty” cell phones to some immigrants near the border.

Rubio blasted critics, calling the phone reports “false and reckless.” In a post on his Senate Web site, he explained that the phones will go to U.S. citizens near the border to report violence to police and federal agents.

“It’s not some effort to provide phone service to anybody,” Rubio said in an interview with conservative radio host Laura Ingraham.

The controversy indicates that Rubio and the three other Republican members of the bipartisan group that authored the proposal will be under immense pressure to strengthen, not weaken, the citizenship requirements.

Under the proposed bill, undocumented immigrants would have to wait 10 years for a chance at permanent legal residency and three more for citizenship. They would have to pay at least $2,000 in fines, along with hundreds of dollars in fees and taxes. And they would be required to learn English, pass criminal-background checks and prove they have lived continuously in the United States and have been employed regularly during that time.

Furthermore, the immigrants must have come to the country before Dec. 31, 2011. Advocates said hundreds of thousands of people who entered the United States in 2012 and 2013 would immediately be ruled ineligible under the Senate’s proposal, meaning those immigrants would continue living in the shadows of society.

Gustavo Torres, executive director of the group CASA of Maryland, said an estimated 400,000 people would be “immediately undocumented as soon as President Obama signs the bill.” He added, “This is very problematic for our people and our community.”

In 1986, the last time the nation’s immigration laws were thoroughly rewritten, an estimated 2.9 million undocumented immigrants were moved to legal status and eventually citizenship, but about the same number were excluded, advocates said.

“Obviously, there are many ways to frustrate and deny citizenship. Cost is one; the length of time to achieve it is another,” said Eliseo Medina, secretary-treasurer of the Service Employees International Union, which supports a path to citizenship. “We need to make sure, first of all, that this bill now delivers on the fundamental promise of actually making citizenship available to everyone.”

The four Democratic senators involved in the legislative proposal briefed a roomful of advocates at the Capitol on Wednesday morning and several attendees pressed the lawmakers on the hurdles to citizenship, according to participants. Sen. Robert Menendez (D-N.J.) offered an impassioned defense, telling them he would not have signed onto the bill if he believed the path was too burdensome.

The senator explained that “bipartisan bills are compromises,” said a Menendez aide who spoke on condition of anonymity to discuss a private meeting. “But he does think this covers the vast majority of people.”

Pamela Constable contributed to this report.

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