WASHINGTON — A proposal to stop potential terrorists from getting a U.S. driver's license may turn the licenses into a national ID card or help the government track gun purchases, opponents fear.

Conservatives, civil libertarians, gun owners and others share such concerns about a House-passed bill that broadly rewrites the rules for licenses and is portrayed as an anti-terrorism tool.

They fear that licenses, like Social Security numbers, could be used for purposes well beyond their original intent.

"Supporters of this don't seem to have the ability to look beyond how this system they are putting in place can change. They can't see how it can metamorphose into a national ID card," said Steve Lilienthal, director of the Free Congress Foundation Center for Privacy & Technology.

The Utah Legislature, with only three days left in the current session, is considering two similar measures.

The first, SB227, would prohibit undocument aliens from receiving a Utah driver's license. Instead, they would receive a driving privilege card, which could not be used as identification at places such as airports.

Utah's Hispanic community has declared the measure discriminatory and a threat to racial profiling.

The second, HB223, would give legal immigrants who aren't eligible to work, such as those on student visas, the ability to obtain a Utah driver's license, or — if SB227 passes — the "driving privilege card."

Nationally, opponents to the federal measure, passed by a 261-161 vote last month and supported by the White House, even could make it possible for the government to monitor people's movements in the country through a chip in a license.

"Supporters of this don't seem to have the ability to look beyond how this system they are putting in place can change. They can't see how it can metamorphose into a national ID card," said Steve Lilienthal, director of the Free Congress Foundation Center for Privacy & Technology.

The House passed the legislation Feb. 10. Supporters promote the bill, which the Senate has yet to consider, as another way to fight terrorism.

Under the measure, states must verify they are giving licenses to U.S. citizens and legal residents. If they fail to do so, federal officers cannot accept licenses from residents of those states as proof of identity to get on an airplane or into a federal building, for example.

Lilienthal, whose think tank says it is politically and culturally conservative, asked what is there to stop the government from eventually requiring information about people's health, criminal backgrounds or gun ownership.