Opponents said the legislation would give the tribes too much power, McClatchy Newspapers reported.
The bill, sponsored by Sen. Patty Murray, D-Wash., would allow tribes to try non-Indians in cases of rape or domestic abuse.
The bill doesn't limit itself to tribal issues. It also would permit federal law officers to aid in the investigation of crimes against gay, lesbian, bisexual and transgender victims and allow more illegal immigrants to get temporary visas to stay in the United States if they have been victimized
The House has passed a version of the bill, but without the additional protections.
Senate Republicans say the bill would pass if Murray dropped her demands to expand its provisions.
Opponents see the bill as an attempt by tribes to expand their land base and judicial authority. They say local law enforcement already has authority to investigate domestic abuse cases on Indian land and make arrests. Non-Indians would lose their rights in tribal courts, opponents contend.
Supporters of the bill said local authorities are sometimes reluctant to investigate crimes committed on Indian land.