Legislators in Nebraska voted Tuesday in favour of retaining the death penalty, but the midwestern state remains without a legal method of putting convicted criminals to death.

The state Supreme Court ruled in February that the electric chair — the only method of execution allowed in Nebraska — is cruel and unusual punishment, and therefore unconstitutional.

The state's Republican governor, Dave Heineman, has appealed the decision. He has also spoken against proposed legislation to replace the death penalty with life imprisonment. That measure was voted down at the state legislature in Omaha by a vote of 28 to 20.

Nebraska was unique among U.S. states that used capital punishment because it only authorized the electric chair, a method of execution that even Heineman had described as "archaic and outmoded."

All of the other 35 states with the death penalty usually use lethal injection to kill criminals convicted of a capital offence. Those with other methods also allow lethal injection to be used in the event of a court ruling similar to that in Nebraska.

Idaho and Oklahoma, for example, still allow death by firing squad if an inmate so chooses, but the method has not been used in decades. Utah, which removed the firing squad from its list of capital punishment options in 2004, last allowed a criminal to be executed by gunfire in 1996.

Lethal injection itself is being questioned in many jurisdictions. Courts in Florida and California have demanded changes in the injection regimen because of accounts of inmates experiencing extreme pain as they die. Illinois is one of several states to declare a moratorium on all executions while the issue of cruel and unusual punishment is explored.

With files from the Associated Press