Updated: 3:36 p.m.President-elect Barack Obama will officially resign his Senate seat on Sunday, a Democratic leadership aide confirmed on Thursday.Obama (D) is the junior Senator from Illinois, having only served four years of his six-year term. Illinois Gov. Rod Blagojevich (D) will be charged with naming Obamas appointment.It has been one of the highest honors and privileges of my life to have served the people of Illinois in the United States Senate," Obama said in a statement on Thursday. "In a state that represents the crossroads of a nation, I have met so many men and women whove taken different journeys, but hold common hopes for their childrens future. It is these Illinois families and their stories that will stay with me as I leave the United States Senate and begin the hard task of fulfilling the simple hopes and common dreams of all Americans as our nations next President.It is unclear when Vice President-elect Joseph Biden, who was elected in Delaware to a seventh Senate term last week, will resign from his seat.Obamas resignation will take effect just as Congress is returning for a weeklong lame-duck session.Last week, Blagojevich (D) formed a panel to vet potential Democratic Senate replacements for Obama, a roster that likely includes Illinois Reps. Jesse Jackson Jr. and Jan Schakowsky, state Comptroller Dan Hynes, state Veterans Affairs Director Tammy Duckworth, former state Senate President Emil Jones, state Sen. Kwame Raoul and marketing consultant Dan Seals, who lost his second consecutive race last week to Rep. Mark Kirk (R-Ill.).Blagojevich said last week that the panel would be made up of diverse senior staff of his administration, but he declined to name names or indicate when the panel would officially convene. Still, the panels recommendations are expected to weigh heavily on the embattled governors ultimate decision, as he balances a delicate mix of racial, legal and political considerations not least of which is his own re-election in 2010.The governors office on Thursday declined to discuss the status of Obamas replacement.