Washington, D.C. ? Caroline Kennedy is interested in the Senate seat that would open once Hillary Rodham Clinton becomes secretary of state, according to a close relative who says the powerful Kennedy clan is fully behind her rising to the office previously held by her uncle.

“I know she’s interested,” Robert F. Kennedy Jr. told The Associated Press in a telephone interview Friday. “She spent a lot of her life balancing public service with obligations to her family. Now her children are grown, and she is ready to move onto a bigger stage.”

Once Clinton is confirmed to President-elect Barack Obama’s cabinet, New York Gov. David Paterson will appoint someone to fill the seat for two years.

The Kennedy family’s connections and history cannot force Paterson to choose Caroline, who is the daughter of President John F. Kennedy. But the family’s strong support could increase pressure on Paterson to choose her above lesser-known contenders.