And of course, in the case of Barack Obama, had he not won primaries - and particularly the heavily important caucus in Iowa - if the public hadn't shown that they were prepared to vote for a black president, we wouldn't have one today.

When he [Franklin Roosevelt] ultimately does not get the Republican Party nomination and decides to start his new Bull Moose Party, he does, for the first time, let black delegates be part of the party from elsewhere in the country.

Reagan, people claimed, was too old to run for president and to be elected. But he proved himself such a vigorous campaigner in the primary system that he overcame those beliefs.

So, in Kennedy's case, he was a Catholic. And people thought after the Al Smith election and so forth that a Catholic couldn't win in the United States. But when he was able to win in West Virginia, he proved that a Catholic could win, even in a heavily Protestant state.

The reverse is a system in which you basically let people who were leaders in one way or another - people sometimes decried as party bosses, people who are part of special interests make the decision. And I think that's a worse system than the one we have.