SOMERS, Conn. —  The Supreme Court (search) lifted an order blocking Connecticut from putting a serial killer to death, clearing the way Friday for New England's first execution in 45 years as it rejected pleas by the man's father to spare his life.

Michael Ross (search), 45, is on death row for the murders of four women and is scheduled for execution early Saturday. He decided last year to drop all appeals and die by injection, but his father and public defenders had waged their own battles to save his life and won a delay earlier this week, arguing that he was not mentally competent to decide his fate.

Death penalty opponents have warned that an execution in liberal New England could have a domino effect across the region and make it easier for other states to put criminals to death.

"Part of me says it's a one-time thing, and we're not Texas," said Robert Nave, head of the Connecticut Network to Abolish the Death Penalty (search). "However, I continue to think this will leave a psychic imprint on the collective psyche that says this wasn't so bad."

Earlier Friday, a federal appeals court said it would give Ross' father until at least Sunday to make his case before the U.S. Supreme Court. But Attorney General Richard Blumenthal asked the Supreme Court to allow the execution to go ahead as planned early Saturday, and the high court agreed.

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"There certainly is no spirit of celebration or joy, simply a sense that the justice system is moving forward," Blumenthal said late Friday.

Protesters planned to march by the hundreds to a point near the prison.

Earlier in the day, Richard Bieder, a partner in the law firm representing Ross' father, complained: "This is supposed to be a civilized society. One wonders why there is this rush to kill a man a day early when what they're doing may be wrong."

Ross, who is to be executed at Osborn Correctional Institution in Somers, Conn., has confessed to killing eight women in all.

Of the six New England states, only Connecticut and New Hampshire have the death penalty.

New Hampshire has not executed anyone since 1939 and has no one on death row. Seven inmates are waiting to die in Connecticut, which conducted New England's last execution in 1960.