A fight to the finish
Definition 1 of 1
Pro Tip 1/3Figurative Use
It often describes non-physical struggles, like intense competitions or arguments. 
The debate was a fight to the finish between the two candidates.
Pro Tip 2/3Express Finality
Emphasizes that an effort or conflict will continue until a clear winner emerges. 
The two rivals were in a fight to the finish for the championship title.
Pro Tip 3/3High Stakes
Suggests there's a lot at stake, with significant consequences for the loser. 
Survival in the industry was a fight to the finish for the small company.