WASHINGTON — Three Democratic senators are demanding civil rights protections for Americans who might be targeted in FBI national security investigations without any evidence of wrongdoing.

In a letter Tuesday to Attorney General Michael Mukasey, the senators also urged the Justice Department to delay still-tentative rules that would expand FBI powers to seek out potential terrorists.

Democratic Sens. Edward M. Kennedy, Dick Durbin and Russ Feingold fear the rules would allow surveillance of Muslim- or Arab- Americans based, in part, on their race, ethnicity or religion.

The senators want the Justice Department to shelve the rules until after a new president takes office.

The rules were the focus of a Senate Intelligence Committee hearing Tuesday afternoon.