The White House issued a veto threat against legislation including attacks motivated by the victims' gender or sexual orientation in federal hate crime law.
The hate crimes bill, with strong Democratic backing, is expected to pass the House of Representatives Thursday. Similar legislation is moving through the Senate.
But the legislation, which also would increase the penalties for bias-based violence, has met outspoken resistance from conservative groups and their Republican allies in Congress, who warn that it undermines freedom of speech, religious expression and equal protection under the law.
The White House, in a statement, said state and local criminal laws already provide penalties for the crimes defined by the bill and "there has been no persuasive demonstration of any need to federalize such a potentially large range of violent crime enforcement."
It also questioned the constitutionality of federalizing the acts of violence barred by the bill and said that if it reaches the president's desk "his senior advisers would recommend that he veto the bill."
The White House also noted that the bill would leave out other classes such as the elderly, members of the military or police officers.
Hate crimes under current federal law apply to acts of violence against individuals on the basis of race, religion, color, or national original. Federal prosecutors have jurisdiction only if the victim is engaged in a specific federally protected activity such as enrolling in school, voting or traveling between states.
The House bill would extend the hate crimes category to include sexual orientation, gender, gender identity or disability.