Conversation so far:
What are Joe Biden's characteristics as Senator?
During his years as a senator, Biden amassed a reputation for loquaciousness, with his questions and remarks during Senate hearings being known as long-winded
Was Joe Biden likable as Senator?
Does Joe Biden have a lot of friends in politics?
Yes; some of Joe Bidens policitian friends have included John McCain, Chris Dodd, President Barack Obama

Question: When did he become senator?
Self-contained rewrite: When did Joe Biden become Senator?