Clinton was ahead only under a fifth scenario excluding caucus states.

He has also visited Iowa, the first caucus state in presidential campaigns.

Forget Iowa; that is a caucus state, pitting committed organizations against each other.

"We want to make sure we're a force in the early primary and caucus states."

"It means the unions are very strong in a caucus state," he replied.

The early primary and caucus states will determine if he will remain a player in presidential politics.

Forget about the long months of campaigning in Iowa, the first caucus state.

In a caucus state, he has to deal with the Democratic activists.

Preferences are based on state laws, party rules, delegates' public statements and projections from early results in caucus states.

In caucus states, most state parties use a two pronged process.