tooth and nail

adverb

1. with all one's resources or energy; fiercely:

   We fought tooth and nail but lost.

tooth and nail

1. To fight “tooth and nail” is to fight with the intensity and ferocity of a wild animal: “The resistance forces fought the invading troops tooth and nail.”

Word History and Origins

Origin of tooth and nail¹

First recorded in 1525–35

Example Sentences

"If you could lock down some of the potential voters who are registered, who are saying, 'I haven't decided yet,' or 'I'm alienated from both candidates,' I think you would see them both, up until the very end, trying to flip those voters and turn them out — tooth and nail to the end."

From Salon

Ms Byrne said she had seen pupils in their final years of secondary school who could "barely read and write" and had had to "fight tooth and nail" to get support for her own child.

From BBC

“Right now, currently, the Valley is just surviving, as is a lot of Los Angeles — just barely surviving and fighting for everything that they can, tooth and nail,” she told LA Progressive earlier this year.

From Los Angeles Times

This argument is tough to swallow, given that RFK Jr. himself is fighting tooth and nail to ensure that millions of other voters are irrevocably deprived of their ability to support him.

From Slate

We fight tooth and nail to keep this band together because we saw the way that U2 were.

From Los Angeles Times