WASHINGTON — The state of Texas appeared set to push forward with the controversial execution of a Mexican national Thursday despite calls for a reprieve from the White House and the Mexican government.

Humberto Leal Garcia, 38, was scheduled to die at 6:00 pm (2300 GMT) in a Huntsville, Texas prison for the rape and murder of a 16-year-old girl in 1994.

The Supreme Court denied his request for a stay of execution just over an hour before he was set to be put to death.

His only chance for a reprieve lies with Texas Governor Rick Perry, a Republican mulling a 2012 White House bid who is a staunch supporter of the death penalty.

A spokeswoman for Perry told AFP that the governor had not yet made a decision about Leal's case.

Perry must rely on the state's parole and pardon board, which voted 4-1 against a reprieve and 5-0 against a commutation.

Mexico maintains Leal was not given proper consular access after his arrest, a violation of the Vienna Convention.

He is one of 51 Mexicans being held in US jails despite a 2004 International Court of Justice ruling that their consular rights were denied.

"With consular assistance, Mr. Leal would likely not have been convicted, let alone sentenced to death," said his lawyer, Sandra Babcock.

Leal -- who is brain damaged -- has maintained his innocence and his defense team has argued that he was convicted with flawed evidence.

They say the murdered girl was under the influence of drugs and alcohol and died accidentally after falling on a rock when Leal tried to help her after she was raped at a party.

In a rare intervention, the US government's top lawyer urged the Supreme Court to spare Leal's life, saying his execution would cause "irreparable harm" to US interests.

"This case implicates United States foreign policy interests of the highest order," US Solicitor General Donald Verrilli wrote in an amicus brief to the top court on Friday.

The execution "would have serious repercussions for United States foreign relations, law enforcement and other cooperation with Mexico, and the ability of American citizens traveling abroad to have the benefits of consular assistance in the event of detention," he wrote.

Amnesty International, the United Nations, and several former US diplomats and military commanders have also called for a stay of the execution.