On July 26, 1969, Kennedy delivered the television speech that saved his senatorial seat. Speaking to the nation for just 13 minutes, he described a cookout "for a devoted group of Kennedy campaign secretaries" and denied the rumors of drunk driving or "immoral conduct."
He acknowledged his failure to report the accident promptly as "indefensible" and described the "irrational" thoughts that consumed him that night, such as wondering "whether some awful curse did actually hang over all the Kennedys."
With the 1970 Senate election looming, he asked the voters what to do next.
In telegrams, letters and telephone calls Massachusetts voters overwhelmingly supported Kennedy's run for Senate, 100-1.
"It saved his bacon," said Klein.
Kennedy easily won by a landslide with 62 percent of the vote, but the scandal dogged him, derailing his presidential bid against Jimmy Carter in 1980, even preventing him from becoming the Democrats' Senate Whip in 1971.
But before July 1969, the youngest son in the Kennedy dynasty was on a clear path to the presidency. The eloquent eulogy for his slain brother Robert, only the year before, had transfixed the nation and, according to polls, 79 percent of all Americans thought he would be the Democratic nominee in 1972.
"There was all this rising, boiling feeling about this meteor getting ready to take off," former Kennedy aide Robert Bates told the Boston Globe recently. "Everybody wanted to be connected with Ted."
In that tragedy drowned the highest aspirations of the last Kennedy son, a reckless personality whose reputation had already been mired by other scandals: expulsion after college cheating and reports of excessive womanizing and drinking.
The political fall-out echoed his first run for Senate in 1962, when his primary opponent, the late Eddie McCormack, sneered, "If his name was Edward Moore instead of Edward Moore Kennedy, he'd be a joke."
Even his own brothers deemed "Teddy" too immature for the Senate seat left vacant by JFK's election in 1960, but were over-ruled by family patriarch Joe Kennedy, according to the new book "The Last Lion" by Boston Globe reporters.
The president-elect asked Massachusetts Gov. Foster Furcolo to appoint family friend Benjamin A. Smith until Kennedy turned 30 in February 1962 and was old enough to run in a special election.
Just days after the televised apology, a Time-Harris poll revealed 51 percent of Americans did not believe Kennedy's explanation of why he was at a party with single girls, how a man so familiar with the island could have taken a wrong turn and how, with a back brace from a 1964 plane crash, Kennedy could have swum the turbulent sea waters to his hotel.
Even those who had faith in the senator worried about his ability to handle a crisis. Friends testified in an inquest that after the accident a confused and crying Kennedy, trying to blame the accident on others begged, "What am I going to do, what can I do?"
Within five days of the accident, Kennedy's lawyers arranged for him to plead guilty to leaving the scene of the accident involving personal injury with a two-month suspended sentence and one-year probation.
No further charges were brought against the senator, even after an inquest that raised numerous questions about Kennedy's account of the events and a grand jury the following year.