This morning on Fox News they ran a graphic that said Democratic vice-presidential pick Joe Biden had been in the Senate since he was 29. Say what? Article 1, section 3 of the Constitution clearly states that "No person shall be a Senator who shall not have attained to the age of thirty Years."
So I went to wikipedia, that quick, if not always scrupulously accurate information source. It says that Biden was born on November 20, 1942 and took his seat in the Senate on January 3, 1973.
That means he WAS thirty when he took office, but he was a couple of weeks shy of thirty when he was elected, and obviously well short of the three decade mark when he first announced his candidacy. That's okay; it's clear from the Constitutional text that one must BE thirty to take a seat in the Senate, but there is nothing preventing one from getting a senatorial campaign going while still in ones twenties.
See Corwin, The Constitution and What It Means Today, 1978 ed., p.10: "It was early established in the case of Henry Clay, who was elected to the Senate before he was thirty years of age, that it is sufficient if a Senator possesses the qualifications of that office when he takes his seat; and the corresponding rule has always been applied to Representatives as well."
On the matter of Henry Clay in the Senate, David Currie gives an account different from Corwin's book. See The Constitution in Congress: The Jeffersonians, 2001, p. 120, n. 238, "Clay had been appointed in midterm (taking his seat in January 1807) to replace John Adair, who had resigned. Born in 1777, he was younger than the Constitution required, and he served--this time--only until (sic) 1807... No one challenged his qualifications." Clay was born in April of 1777, so clearly he was only twenty-nine when the January 1807 senatorial session convened.
Notice that Corwin has Clay elected to the Senate before he was thirty; Currie, citing the Biographical Directory of the United States Congress, says Clay was appointed, and that he actually did hold office before his thirtieth birthday. Never mind Clay as a precedent for someone in his twenties running for Senate, Clay actually was a Senator before he was constitutionally eligible.
As for Biden--did you notice given his birth date that when he first ran for president he was actually younger than Barack Obama is now? My memory may be faulty, but I don't recall people making much of an issue of Biden's youth in the 1988 campaign. If my recollection on that is accurate, I would suggest there were three reasons for the lack of focus on Biden's age back then:
1. He had been in the Senate for about sixteen years, for goodness sakes, so no one could say he was young AND inexperienced--which is usually what people mean when they say someone is too young for something, and,
2. Al Gore ran for president the first time in 1988, and he was only forty, so there was someone even younger than Biden gunning for the White House, and
3. Biden shot himself in the foot and dropped out early anyway, well before he gained sufficient support to warrant much scrutiny about anything.