On January 2, 1960, Sen. Kennedy, speaking in the US Senate Caucus Room, made a short speech announced that he was running for president. The full text is here, as well as a link to listen to it.
It was already the election year, which is a measure of the creep of the presidential-election cycle in more recent years. After all, John Edwards just announced his bid for the presidency in 2008, a year-and-change before the first primary. That might give candidates more time to raise money, but do voters really want to hear about it in odd-numbered, non-election years? (Vice President Nixon, incidently, announced his candidacy exactly a week after Sen. Kennedy.)
Kennedy, though backed by a formidable organization and a lot of his father’s money, didn’t have the nomination in the bag so early in the race. In fact, even by the opening of the Democratic National Convention in the summer of 1960, he didn’t quite have the delegates he needed, the last time that was the case for a major party candidate seeking the nomination – another measure of how things have changed in less than 50 years.