They are using something that already exists. Your SS #.
While it is true that the Employment Eligibility Verification System proposals do intend to utilize SSNs as a national identifier (contrary to federal law), this is a minor point, since EEVS is designed to eventually make a REAL ID card mandatory for the employment of every working American.
But even this is a secondary concern. Regardless of the particular identification method used, the fact remains that the proposals greatly expand the power of the federal government by giving it unprecedented oversight over every American's livelihood. Under EEVS, the Department of Homeland Security would determine who is allowed to work, and set the criteria used, with no accountability. The DHS would receive confidential IRS tax information on every worker. "Employer" is defined so broadly as to deny you the right to hire a person for even household services, unless you comply with EEVS. Worst of all, you could be denied the right to work due to clerical error or computer glitch (as evidenced by the error-prone pilot program), or by refusing to divulge personal information or biometric data.
I don't believe most Americans would find this an acceptable remedy to our illegal immigration problem.
It is unfortunate that Congressman Hunter, along with Rep. Tancredo (surprisingly), appear to have joined Mitt Romney and John McCain in advocating something so unnecessary and dangerous. I respectfully invite the good Congressman to explain his position on this. Thanks for your time!