The Mississippi Senate has voted to add gas chamber and electrocution as execution options in case courts block the state from obtaining lethal injection drugs.

Lethal injection is Mississippi's only execution method. The state faces lawsuits claiming drugs it plans to use would violate constitutional prohibitions against cruel and unusual punishment.

The House voted Feb. 8 for House Bill 638 to add firing squad, electrocution and gas chamber. A Senate committee removed firing squad Feb. 23. Amid opposition, the Senate voted Thursday to return the bill to the House.

Mississippi hasn't been able to acquire lethal drugs it once used, and its last execution was in 2012.

The Death Penalty Information Center says of 33 states with the death penalty, only Oklahoma and Utah have firing squad as an option.