Amid all the chaos on Capitol Hill -- a possible vote to impeach Vice President Dick Cheney one day, shenanigans over the annual spending bills the next -- one constant has been the prolonged, backroom negotiation over the State Children's Health Insurance Program (SCHIP).

Presiding over the negotiations are powerful House Democrats such as House Majority Leader Steny Hoyer (D-Md.) and maverick Republican Sens. Chuck Grassley (Iowa) and Orrin Hatch (Utah). Across the table sit two dozen House Republicans who have indicated a willingness to "negotiate"" over such issues as whether a program designed to deliver health coverage to children in families slightly above the poverty level should cover adults, children from middle-class families earning more than $62,000, and illegal immigrants.

Yes, illegal immigrants.

This last issue promises to be the most difficult one to resolve. And it points to the resiliency of immigration-related issues, especially those that involve spending taxpayer dollars.

Democratic pollsters James Carville and Stanley Greenberg believe voter concerns over illegal immigration explain much of the current voter discontent. These concerns have created what they call "a welfare moment.""

"Just as many workers with moderate incomes, uncertain employment and health insurance could not understand why they were being taxed to subsidize the long-term idleness of those on welfare,"" Carville and Greenberg write, "many Americans are just as perplexed that this country has lost control of the borders and winks at illegal employment, taxing the resources of local schools and hospitals."" The frustration extends to health care. One voter lamented: "We can't afford to do anything because we're paying for health insurance,"" yet illegal immigrants "just go in and get it free.""

The last thing lawmakers want to do in this heated environment is create a new health benefit for illegal immigrants even as millions of native-born American children remain uninsured. Because the issue is "binary"" -- an illegal is either eligible for health services or is barred from receiving benefits; no middle ground exists -- it doesn't lend itself to traditional legislative logrolling.

And that's where the political hand-wringing begins.

"House Democratic leaders,"" Congressional Quarterly reports, "may have only limited flexibility to negotiate"" because liberals, black and Hispanic members "have already expressed frustration that the bill Bush vetoed was itself a compromise."" When rumors circulated that House leaders were contemplating language to require tough proof-of-citizenship requirements for SCHIP enrollees, representatives of the several race-based congressional caucuses as well as other "progressive"" members jumped into action. They sent Speaker Nancy Pelosi a strongly-worded letter warning against further concessions, especially, CQ reported, "on immigration issues.""

"We are deeply concerned,"" they wrote, "by the continued compromises we may be asked to make on behalf of our communities."" "Such compromises,"" they warned, "cause us to question our support for the overall package.""

These members like the vetoed SCHIP bill because it would weaken the citizenship and identity verification requirements in current law to prevent illegal immigrants from enrolling in SCHIP. Current law places the burden on citizens and nationals to provide the documentation necessary to prove their citizenship and their eligibility for programs such as SCHIP.

Under the vetoed bill, states would be required simply to run the names and Social Security numbers of applicants through a national database. But, according to Michael Astrue, the Commissioner of the Social Security Administration, this approach would "create a conclusive presumption [that a person is a citizen] based on less reliable data."" This approach, he explains, wouldn't detect legal aliens who are not naturalized citizens. Nor would it verify that the person submitting the information is who he says he is, whether he is fraudulently using another person's valid name and Social Security number, or whether he has illegally overstayed a work visa.

Other than that, it's foolproof!

With memories of last spring's national uprising against the Senate's comprehensive immigration bill still fresh, wavering Republicans fear a potential backlash from constituents should they agree to open the door even a little on this issue.

This episode underscores the need for standard legislative language barring illegal immigrants from receiving federal benefits of any kind. Such language could easily be adapted to any bill that reauthorizes or expands an existing federal program, or creates a new one. Over time, such language would provide a "Good Housekeeping Seal of Approval"" against loophole-ridden provisions such as those now in SCHIP.

The "welfare moment,"" it seems, has arrived.

Michael Franc is vice president of government relations for The Heritage Foundation (heritage.org).