By TODD RICHMOND, Associated Press

MADISON, Wis. (AP) — Four years after relaxing the state's iron mining laws, Wisconsin Republicans are pushing to lift a moratorium on copper and gold mining — a ban Gov. Scott Walker helped impose as a legislator.

Wisconsin law requires sulfide mining applicants to prove a similar mine has operated for 10 years and been closed for 10 years without polluting. No companies have provided any examples.

Sen. Tom Tiffany has introduced a bill that would eliminate the moratorium as well as exempt large-scale sampling from environmental impact statements and weaken the contested case hearing process. Tiffany was the chief sponsor of a 2013 bill that dramatically loosened the state's iron mining laws.

Walker voted for the moratorium when he was in the state Assembly in 1998. His spokesman said only that Walker would review the bill if it reaches his desk.