Support for Death Penalty Down

May 2 -- Virginia state Sen. Frank Hargrove, a conservative Republican, once campaigned for public hanging. Recently, he changed his mind: "Better to let 10 people go than convict and execute one innocent person."

In Texas, where 445 inmates sit on death row, state Sen. Eliot Shapleigh now wants to stop executions for two years while officials study whether they are carried out fairly. "We as a society need to be pretty sure we're correct when we do it," he said.

This year, major campaigns to suspend executions have been launched in 19 states.

When ABCNEWS' polling unit asked people if they would support a nationwide "halt in all executions" while a commission studies if they're "administered fairly," 51 percent of Americans supported it.

Florida's former Chief Justice Gerald Cogan changed his mind on the death penalty because, he says, the courts kept making mistakes. "If you find out that you've executed an innocent person, you don't go to the same cemetery, dig up the coffin, open up and say, 'Sorry, we've made a mistake,'" he said.

Why the Decline?

If you ask Americans simply whether they "approve of the death penalty," a majority — 63 percent — still say yes. But when you offer the option of life in prison with no chance of parole, support for executions now drops to less than half.

One reason for the decline is growing worry that the court system keeps making mistakes and applies the law unevenly. "I've come to the conclusion that in Texas, indeed anywhere I've looked at, we apply it unfairly," said Shapleigh.

The new poll does find large majorities now say the death penalty is unfair because it is applied differently from county to county and state to state. And it's unfair because innocent people are sometimes executed, they say.

Majority Say Executions Don't Deter Crime

Another big reason for the decline is the belief that the death penalty is a deterrent to crime has dropped sharply in recent years — from nearly two-thirds to well under half today.