Question

complete the sentence with the word that best fits the overall meaning and tone.
the mayor had been a ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​ of the castroville government for decades, so he was missed when he returned to his law practice.
mainstay
proponent

Explanation:

"Mainstay" means a person or thing that is very important and provides a lot of support. The mayor was in the government for decades and was missed when he left, indicating he was a crucial part (mainstay). "Proponent" means a person who supports or advocates for something. But the context emphasizes his long - term and essential role in the government, not just his advocacy.

Answer:

mainstay