Joe Biden, the president-elect of the United States, previously served in the United States Senate from 1973 through 2009. A member of the Democratic Party from Delaware, Biden was first elected to the Senate in November 1972, and sworn into office at age 30 on January 3, 1973; he was reelected six times. He resigned on January 15, 2009, five days before becoming vice president of the United States during the presidency of Barack Obama.
The Senate.
Here. Let me Google that for you, bud.
https://en.wikipedia.org/wiki/United_States_Senate_career_of_Joe_Biden
You next, probably : Who is Barack Obama?