Cory Booker was sworn in by Vice President Joe Biden as the new Democratic senator from New Jersey early Thursday afternoon.
Booker, a former mayor of Newark, N.J., was elected to the Senate in a special election earlier this month to fill a vacancy created by the death of the late Sen. Frank Lautenberg, D.
Booker becomes the second African-American member of the Senate, along with Sen. Tim Scott, R-S.C.
"I urge my fellow senators, Democratic and Republican, to get to know this good man. I feel so elated that he's here," Senate Majority Leader Harry Reid, D-Nev., said before Booker took the oath of office. "We're going to find that Cory Booker is going to be a great asset to this nation and to the Senate."
Booker is regarding as a rising Democratic star, having won national attention for his efforts to turn around crime and poverty in Newark during his time as mayor. An ally of President Barack Obama, Booker also forged an unlikely partnership with New Jersey's Republican governor, Chris Christie.
With his inauguration, Booker slightly changes the balance of power in the Senate back to what it was before Lautenberg died; Christie appointed a Republican, Jeff Chiesa, as an interim senator before Booker was elected.
Now, the Senate's membership consists of 53 Democrats, 2 independents who caucus with Democrats, and 45 Republicans.