"I think the turning point came when people looked at my credentials and saw my desire to serve," Burris said Tuesday on CNN's "American Morning."

Burris, a former Illinois attorney general, said he knew all along his appointment to the Senate was legal, despite federal corruption charges against Illinois Gov. Rod Blagojevich.

Some Senate Democrats initially believed Burris should not be certified for the seat because he was appointed by Blagojevich, who was impeached by the Illinois House Friday for allegedly trying to sell the seat, among other things. The governor has maintained he is innocent.

Burris said his life's purpose is to be a public servant and he feels "truly humbled and honored" that Senate Democrats have agreed to seat him later this week.

Burris is held in "high regard" by President-elect Barack Obama, said Dan Pfeiffer, a spokesman for Obama's transition team.