HUNTSVILLE, Texas (CNN) -- A last-ditch push to keep a convicted cop killer alive in Texas failed Wednesday night when the U.S. Supreme Court denied a motion to stay his execution.
The execution by lethal injection of Edgar Tamayo Arias, a Mexican national, is scheduled to proceed Wednesday night, Texas Department of Criminal Justice spokesman Jason Clark said.
Mexico's government has been pushing to block Tamayo's execution, arguing that it would violate international law.
Lawyers for Tamayo criticized the Supreme Court's ruling.
"He will be executed tonight, despite the indisputable fact that his right to consular assistance was violated," attorneys Sandra L. Babcock and Maurie Levin said in a statement.
Arias, 46, was convicted of the 1994 murder of a Houston police officer.
His supporters say he was denied access to his consulate when arrested, as required by an international treaty.
Earlier Wednesday, the state's Board of Pardons and Paroles denied Tamayo's clemency request.
The Bush and Obama administrations had urged Texas and other states to grant Tamayo and inmates in similar situations new hearings, fearing repercussions for Americans arrested overseas.
Since 2008, Texas has executed two other Mexicans convicted of murder who raised similar claims. The Supreme Court refused to delay either one.
Tamayo's lawyers argue the consulate access violation was more than a technicality -- that Mexican officials would have ensured he had the most competent trial defense possible, if they had been able to speak with him right after his felony arrest.
Houston police officer Guy Gaddis was fatally shot after arresting Tamayo and another man for robbery.
Tamayo is one of 40 Mexican citizens awaiting the death penalty in U.S. prisons.
Mexican officials made similar consular-access arguments -- unsuccessfully -- before executions in 2008 and 2011.
U.S. Secretary of State John Kerry has also weighed in on Tamayo's case, arguing that setting an execution date is "extremely detrimental to the interests of the United States."
"I want to be clear: I have no reason to doubt the facts of Mr. Tamayo's conviction, and as a former prosecutor, I have no sympathy for anyone who would murder a police officer," Kerry wrote. "This is a process issue I am raising because it could impact the way American citizens are treated in other countries."
Lucy Nashed, a spokeswoman for Texas Gov. Rick Perry, said the state was committed to enforcing its laws.
"It doesn't matter where you're from --- if you commit a despicable crime like this in Texas, you are subject to our state laws, including a fair trial by jury and the ultimate penalty," she said.
-- CNN's Gustavo Valdes reported from Huntsville. CNN's Bill Mears reported from Washington and CNN's Catherine E. Shoichet reported from Atlanta. CNN's Nick Parker and Mayra Cuevas contributed to this report.
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