From this:

A "forgery-proof" worker ID card, secured with biometric data such as fingerprints, is an idea favored by Sen. Charles E. Schumer (D-N.Y), the new chairman of the immigration subcommittee. Schumer, who will lead the effort to craft the Senate's comprehensive immigration overhaul legislation, called the card the best way to ensure that all workers were authorized.

"The ID will make it easy for employers to avoid undocumented workers, which will allow for tough sanctions against employers who break the law, which will lead to no jobs being available for illegal immigrants, which will stop illegal immigration," Schumer wrote in his 2007 book, "Positively American."

"Once Americans are convinced that we will permanently staunch the flow of illegal immigration, they will be more willing to accept constructing a path toward earned citizenship for those who are already here."

Rather than repeating myself, see August 18, 2007's Thanks, liberals & libertarians: 71% support "foreigners-only" ID card. If "liberals" and libertarians would support our more-than-reasonable immigration laws, Schumer wouldn't have a leg to stand on. As it is, he might be effective, and all those who continue to support massive illegal activity in the name of "freedom" will have made the U.S. a lot less free. Don't trust those who can't figure out or who won't disclose the downsides of what they promote.