"Everything that's happened in the last week and a half is just strength for carrying on the duties," said Chafee, the Republican mayor of Warwick, R.I., at a reception following the Senate chamber ceremony.
Vice President Al Gore administered the oath to Chafee, who had been appointed Tuesday by Rhode Island Gov. Lincoln Almond.
In making the appointment, Almond said that Chafee, the Republican mayor of Warwick, was the best qualified for the seat.
Chafee, 46, had announced his candidacy for the seat earlier this year after his father said he would not seek a fifth term in 2000. Now the younger Chafee will run as the incumbent.