New Jersey's Cory Booker, the former Newark mayor, is the U. S. Senate's newest member.
Vice President Joe Biden administered the oath to Booker, 44, Thursday. That boosted the Senate's Democratic majority to 55 seats. He will be the only Democratic African-American in the Senate.
Booker won a special election earlier this month for the seat of veteran Sen. Frank Lautenberg, D-N.J., who died earlier this year. Lautenberg died in June, and Sen. Jeffrey Chiesa, R-N.J., was named to replace him until the special election
Before the swearing-in, Senate Majority Leader Harry Reid praised Booker as someone who knew how to stay in touch with constituents.
"He's lived with his constituents and kept in touch with them like no mayor I've ever come in contact with," Reid said. "He has been with them in the inner city of Newark."