Asked for his last words Allen, 56, volunteered, "Obama won two out of three counties. It's going to be a very close race," CBS Houston reported, citing the McAlester News-Capital newspaper.
Allen's statement was followed by saying hello to his attorneys multiple times, as well as several unintelligible words about Obama and Jesus Christ.
He was reportedly declared dead at 6:10 p.m., after the doctor administering the lethal injection drugs began to do so at 6:07 p.m., as one of his attorneys shed tears, CBS Houston reported.
Allen was convicted of murdering his 24-year-old wife, Lawanna Gail Titsworth, in 1986 - four days after she moved herself and their two young sons out of their shared home.
Allen's execution had been stayed multiple times, the McAlester News-Capital learned, under the Oklahoma and United States Supreme Court's law prohibiting the execution of insane or otherwise mentally incompetent inmates.