PUZZLE 017 Three's a Crowd

Three candidates (A, B and C) are standing for mayor in an election with 1000 voters.
In a pre-election poll, 200 voters were undecided, 400 voters supported A, 300 voters supported B, and 100 voters supported C.
Assuming no votters changed their allegiance, how many candidates out of the three still have a chance of winning the election?

Hint 1

Candidate A was the winner of the pre-election poll.
But that was just a poll.

Hint 2

Elections are based on votes that are actually cast.

Hint 3

In the actual election, voter turnout is a consideration.
Not all of the 1000 electorate will necessarily vote.

Super Hint

The pre-election poll results and the views of the electorate have not changed, but we don't know how many of the one thousand people polled ended up actually voting in the proper election.
The result could vary dramatically depending on who turned up to vote.

Answer for 'Three's a Crowd'

The answer is '3'.