BOSTON -- Interim Sen. Paul Kirk said goodbye and thanked his colleagues in the U.S. Senate Thursday hours before Scott Brown would take over the seat formerly held by the late Ted Kennedy.

Kirk, the former Massachusetts Democratic Party chair, had been holding the seat temporarily on an appointment from Gov. Deval Patrick after Kennedy's death in August.

"My appointment to this office has allowed me to serve my Commonwealth and country in ways I could not have imagined just a few months ago," Kirk said. "It has enabled me to work closely with many old and new Senate friends -- women and men who have been sent by their constituents to work together to make our nation a better place."

In his farewell speech, Kirk thanked his colleagues in the Senate and state lawmakers in Massachusetts.

"I discovered, when just a boy, how emotionally difficult it was to say the words good bye. So, I learned to use two other words that come much easier at times like these, and that more appropriately express what I wish to say to those who may be listening. Those two words are: thank you," Kirk said.

Kirk urged the Congress to continue its work on health care reform, and not allow too much ""dust to settle on the issue.

"This 111th Congress must not let so much dust settle that it buries all the sensible and necessary ideas that have been suggested," Kirk said. "Comprehensive health care reform must remain an urgent priority of this Congress."

Brown, a Republican, defeated Attorney General Martha Coakley in a special election to permanently fill Kennedy's seat. He was scheduled to be sworn in on Thursday afternoon.