ALBANY, Oct. 15 — In a hearing punctuated by angry exchanges about terrorism, Senate Republicans grilled the commissioner of the Department of Motor Vehicles on Monday, pressing him to defend Gov. Eliot Spitzer ’s plan to grant driver’s licenses to illegal immigrants.
Senator Vincent L. Leibell, an upstate Republican, declared that under the proposal, Osama bin Laden could obtain a driver’s license in New York.
The commissioner, David J. Swarts, shot back, "I think we’d probably catch that right away."
Mr. Swarts then cracked, "At least we’d know where he is," echoing a newspaper column on the subject.
The four-hour hearing underscored the contentiousness over the issue, which is emerging as a major political firefight in the capital and beyond. Lou Dobbs has taken it up as an almost nightly cause on CNN.
Republicans are threatening to cut off money for the D.M.V. if Mr. Spitzer goes ahead with the policy. Many Democratic politicians are either voicing their disapproval or quietly expressing worry that the governor has prompted voter anger and unnecessarily imperiled their chances in the 2008 election.
On Monday, a poll conducted by Siena College was released showing overwhelming opposition to the plan, with 72 percent of New Yorkers opposing it. The poll also showed the governor’s job approval numbers weakening.
Republicans questioned whether technology measures being put in place could be effectively used in motor vehicle offices to check the authenticity of a myriad of foreign passports. Beyond terrorism concerns, they said the policy would in effect condone breaking immigration laws.
The governor has said his policy would make the state more secure by bringing hundreds of thousands of illegal immigrants out of the shadows, allowing the state to maintain records on them. He has also said it would improve traffic safety and lower insurance costs by encouraging illegal immigrants to obtain licenses and insurance.
Mr. Spitzer said at an appearance on Monday that he was undaunted by the opposition.
"It’s what happens when you govern and make tough decisions, and do things that you believe are right, and don’t govern based on polls," Mr. Spitzer said.
The hearing also vividly reflected the racial politics bound up in the proposal. The 10 Republicans on the two Senate committees running the hearing were all white men, and were in the middle, while the 5 Democratic members, all but one black or Hispanic, were relegated to the far ends of the hearing table.
Republicans scheduled a dozen opponents of the plan to follow the commissioner.
"Every single witness that they have invited today are in opposition," said Senator Ruben Diaz Sr., a Bronx Democrat, while Senator Bill Perkins, a Harlem Democrat, criticized Republicans for fostering the "politics of fear-mongering."
The standoff is most likely to lead to a number of fights in the courts and over the division’s budget. While the governor’s staff has said it has the authority to begin granting the licenses without the Legislature’s approval, Senate Republicans are threatening to withhold money for the new personnel and technology that would be needed to put the plan into effect.
Republicans are also threatening to sue to block the proposal. And about a dozen county clerks have said they would refuse to go along with the plan, and several of them, including one Democrat, appeared at Monday’s hearing. The clerks’ offices in many upstate counties double as D.M.V. branches, and the governor has threatened to take legal action against them if they do not carry out his policies.
"This plan makes it easier, far easier, for driver’s licenses to fall into the wrong hands, like those of potential terrorists," said Kathleen Marchione, the Saratoga County clerk who is the president of the New York State Association of County Clerks.
The clerks and some other officials have questioned why the governor did not move more slowly and obtain more public input in putting forward the plan.
On Monday, Senate Republicans pressed Mr. Swarts to urge the governor to reconsider, saying it would weaken security measures put in place since the Sept. 11 attacks.
The governor’s plan is similar to one in place in eight other states, but runs counter to a trend in a majority of states to explicitly bar illegal immigrants from obtaining licenses.
"There seems to me to be a bit of arrogance here in jamming down the public’s throat that this is good for you," said Senator Thomas W. Libous, a Binghamton Republican and one of Albany’s more mild-mannered politicians. "And at this point I see no harm in recommending to the governor, let’s just hold on a minute."
Mr. Spitzer has stressed that illegal immigrants would have to show a valid foreign passport to obtain the license, and Mr. Swarts urged the senators to accept that illegal immigrants live here and that the state government has to deal with that reality.
Mr. Swarts said there are at least a million illegal immigrants in New York. "They are here to stay," he added. "Many of them participate in the economic viability of the state; to ignore their presence raises some questions."
But the Republicans appear determined. Senator Martin Golden, a Brooklyn Republican, vowed "this governor will not get away with this."
And despite Mr. Swarts’s certainty that Osama bin Laden will not be getting a New York driver’s license, Senator Leibell was not convinced.
"I’m not so sure," said Senator Leibell, adding, "I will tell you this, you would be quite embarrassed if that happened."