The White House strengthened its stand Friday against health-care coverage for illegal immigrants and a pivotal Senate committee looked ready to follow its lead.

The developments reflected a renewed focus on the issue in the days since a Republican congressman's outburst during President Barack Obama's health-care speech to Congress on Wednesday night. Republican Rep. Joe Wilson of South Carolina shouted "You lie!" as Obama said illegal immigrants wouldn't be covered under his health plan.

Democrats had pointed to provisions in House and Senate legislation that prohibited illegal immigrants from getting federal subsidies that would be offered to lower-income Americans to help them buy insurance.

That didn't go far enough for Wilson or many other Republicans, who noted the absence of any enforcement mechanism or requirement for verification of legal status. There are about seven million illegal immigrants in the U.S. who lack health insurance, according to the Pew Hispanic Center.

The issue has caused heat on talk radio and at congressional town halls, too. So on Friday, White House press secretary Robert Gibbs sketched a new position that goes even further than some conservative critics had demanded: Obama will oppose letting illegal immigrants buy insurance through new purchasing exchanges the government will set up — even from private companies operating within the exchanges.

"Illegal immigrants would not be allowed to access the exchange that is set up," Gibbs said. Verification requirements are "something we'd work out with Congress," he said.

Currently illegal immigrants are barred from government-funded care except in certain emergency cases, but many buy private insurance and there's nothing to prevent them from doing that. That would change under the White House's proposal, which is certain to alarm some on the left.

White House officials contended that the policy didn't represent a change of position for Obama, but it's one he apparently hasn't articulated in the past. In his speech Wednesday, Obama said only that "the reforms I'm proposing would not apply to those who are here illegally."

The proposed new marketplace, or exchange, would allow consumers and small businesses to shop for insurance and compare prices in a regulated, competitive environment. The exchange has been built into all the health bills moving through the House and Senate.

Private companies could offer health coverage through the exchange if they meet certain criteria and if Congress created a new government-run plan that would be offered through the exchange, too.

Illegal immigrants were to be allowed in the exchange and even in the public plan if they used their own money under legislation that passed three committees in the House and one in the Senate. Before Friday, there was little indication that that would change, even in the crucial Senate finance committee, which is facing a deadline of early next week to complete a comprehensive health bill.

In explaining its new position, the White House said illegal immigrants could continue to buy insurance in the private insurance market outside the exchange, which would shrink with the creation of the exchange but still exist.

The United States is the only developed country without a universal program of health-care coverage. While many Americans are dissatisfied with the health-care system, attempts to change it are politically explosive.