At least one roadblock stands in the way of Vermont's path toward becoming the first state to adopt a single-payer health care system: coverage for illegal immigrants.

The state Senate, which passed its version of the bill this week, added a last-minute provision that would bar illegal immigrants from being covered under a state-run insurance program the bill envisions setting up called Green Mountain Care.

The move outraged immigrant advocates.

"When we say health care is a human right, we mean for everybody who lives and works in Vermont regardless of legal status," the Vermont Workers' Center said in a statement."We will not tolerate racial profiling and accept the unjust immigration and foreign policies of the federal government. We can do better than that."

The bill is currently in a conference committee in which differences between House and Senate versions are being worked out. The House passed its version last month.

The Vermont Workers' Center and other groups have been lobbying against the Senate amendment under the rhetorical battle cry "Vermont is not Arizona!"

"We as Vermont are one community, and are proud to distinguish ourselves from states like Arizona that pass legislation excluding people based on their immigration status," one activist wrote in an e-mail to state Sen. Richard Sears, a Democrat and amendment sponsor.

Arizona last year passed a law requiring police to question people's immigration status while enforcing other laws if there is a reasonable suspicion they're in the country illegally. A court blocked the law from taking immediate effect after the U.S. Justice Department filed suit saying the federal government has sole jurisdiction over immigration law.

The lobbying effort in Vermont has angered senators who say they supported the amendment merely to clarify something they thought was in the bill already. They add that the special federal permissions -- or waivers -- Vermont needs to implement the health care law won't be forthcoming if the state does not follow the federal lead in excluding illegal immigrants.

"We wouldn't provide membership in Green Mountain Care to someone from Iowa who was here temporarily, so why would we do so for someone here illegally, who by definition is here temporarily?" asked Sen. Randy Brock, R-Franklin, one of the amendment's sponsors.

Another concern is how guaranteeing health insurance coverage to illegal immigrants might affect the program's budget.

"We passed a bill to provide Vermonters with universal health care, not to have Vermonters provide the universe with health care," Brock said.

The issue has struck a chord with a broad swath of human rights supporters and has raised what has been a key immigration issue in the state in recent years: the estimated 1,500 to 2,500 immigrant farmworkers who provide crucial labor to the state's dairy farms but who often remain in hiding for fear of deportation.

The legislation calls for setting up a health care "exchange," or marketplace in keeping with the federal health care law passed last year. The Vermont bill also sets up a state board that would review and approve designs for a publicly financed health insurance program available to all Vermonters.

If passed, the single payer system would draw plenty of scrutiny after being the subject of intense debate during the battle over national health care.

Liberals pushed for a total government-run health care system that mirrored Canada's, which pays for all medical costs .Supporters say this system eliminates administrative waste because it forces doctors and hospitals to bill one entity for services instead of several private insurers that have different billing procedures.

But President Obama and other Democratic leaders resisted those calls, saying a single-payer system was too radical. They did flirt with the possibility of a "public option," or a government-run insurance plan that would compete with private insurers. But in the end, even that didn't make the final cut.

The Vermont plan aims to controls rising health care costs and extend coverage to the nearly 500,000 uninsured Vermonters, even though half of them are eligible for state coverage.

The earliest that the plan could go into effect is 2014, when the state could get a waiver from the federal health care law to establish its own system.

But the Physicians for National Health Program, a group of 18,000 doctors who support a single-payer program on the national level, says the Vermont legislation falls short

"The Vermont plan promises a public program open to all residents of the state in 2017, but even then it would allow a continuing role for private insurance," the group said in a statement earlier this month. "This would negate many of the administrative savings that could be attained by a true single-payer program, and opens the way for the continuation of mult-tiered care."

A survey this month showed a quarter of the state's doctors would leave Vermont if a single-payer system is adopted. The survey, conducted by state Rep. George Till, a Democrat who supports single-payer, showed 44 percent of doctors support it compared with 46 percent who are opposed.

The Associated Press contributed to this report.