As usual, the last player to make a legal move is the winner.
The party has apparently made no new legal move but is expected to challenge it.
The game ends when both players have no legal moves.
But if a player has no legal move, he loses the game.
But there is a real problem for the President in that legal move.
Each player must always have the ability to perform a legal move.
The game ends only when one player has no legal move.
The normal way to win the game is to be the last player left with a legal move.
The game is over when both players have no legal moves left.
The king does not end up in check (true of any legal move).