wrote that "the facts of the assassination itself are simple, so simple that many people believe it must be more complicated and conspiratorial to be true." Warren told the Commission staff not to worry about conspiracy theories and other criticism of the report because “history will prove us right.” Retirement By 1968, Warren was ready to retire from the Court. He hoped to travel the world with his wife, and he wanted to leave the bench before he suffered a mental decline, something that he perceived in both Hugo Black and William Douglas. He also feared that Nixon would win the 1968 presidential election and appoint a conservative successor if Warren left the Court later. On 13 June 1968, Warren submitted his letter of resignation to President Johnson (who made it official on 21 June), effective upon the confirmation of a successor. In an election year, confirmation of a successor was not assured; after Warren announced his retirement, about half of the Senate Republican caucus pledged to oppose any Supreme Court appointment prior to the election. Johnson nominated Associate Justice Fortas, a personal friend and adviser to the president, as Warren's successor, and nominated federal appellate judge Homer Thornberry to succeed Fortas. Republicans and Southern Democrats joined together to scuttle Fortas's nomination. Their opposition centered on criticism of the Warren Court, including many decisions that had been handed down before Fortas joined the Court, as well as ethical concerns related to Fortas's paid speeches and closeness with Johnson. Though the majority of the Senate may have favored the confirmation of Fortas, opponents conducted a filibuster, which blocked the Senate from voting on the nomination, and Johnson withdrew the nomination. In early 1969, Warren learned that Fortas had made a secret lifetime contract for $20,000 a year to provide private legal advice to Louis Wolfson, a friend and financier in deep legal trouble. Warren immediately asked Fortas to resign, which he did after some consideration. Nixon defeated Hubert Humphrey in the 1968 presidential election and took office in January 1969. Though reluctant to be succeeded by a Nixon appointee, Warren declined to withdraw his letter of resignation. He believed that withdrawing the letter would be "a crass admission that he was resigning for political reasons." Nixon and Warren jointly agreed that Warren would retire in June 1969 to ensure that the Court would have a chief justice throughout the 1968 term