Use "lynchpin" in a sentence

1. The National Education Association, a lynchpin in the structure of the Democratic Party, plays a key role in this battle for the moral high ground

2. I realized much later on that it was also the lynchpin that had set everything in motion: the old woman at the tomato bin, the figure in the mirror, and finally the appearance of the myth itself

3. One was the entire lynchpin of WW2 was that is was supposed to be a ‘good’ war