fight tooth and nail
Engage in vigorous combat or make a strenuous effort, using all one's resources. For example, I'm going to fight tooth and nail for that promotion. This expression, with its allusion to biting and scratching, was first recorded in 1576.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.