a fight to the finish

Any struggle for success (as a contest, competition, match, debate, election, argument, etc.) between two or more people that remains closely and vigorously fought until one party is defeated at the very final moment. With her opponent's sudden surge in the polls, it looks like this election is going to be a fight to the finish. It was truly a fight to the finish, with New England managing a field goal in the final seconds of the game to secure their victory. Everyone thought the gubernatorial election would be a landslide victory for the incumbent, but it turned out to be a fight to the finish after news of his scandal broke.

a fight to the finish

a fight, contest, or match which only ends with the complete defeat of one of the parties involved.