There's been plenty of speculation that Vice President-elect Joe Biden would love to see his son, Delaware Attorney General Beau Biden, take over his soon-to-be vacated Senate seat, NBC News's Doug Adams writes. Some believed that Biden may wait to resign his seat in a maneuver -- giving newly-elected governor Jack Markell the power to appoint rather than outgoing-Gov. Ruth Ann Minner -- aimed at helping that happen. However, with Obama's resignation from the Senate yesterday, Biden may be pressured to resign soon.

With the younger Biden scheduled to be deployed to Iraq for about a year, a place-holder would be needed for the next two years -- someone who wouldn't challenge Beau in a 2010 special election. One person mentioned is outgoing-Lt. Gov. Jack Carney.

From NBC News:

With all of this swirling, Obama's resignation Sunday is putting a lot of pressure on Biden to announce his intentions soon, several Delaware political observers tell NBC News. Waiting to resign could be seen as unseemly -- an obvious political ploy to manipulate the system and clear the way for his son.

So the likely speculation now -- and that's all it is at this point -- is that Joe Biden will step down sooner rather than later, and allow outgoing Gov. Minner to name his successor.

For those who care -- any appointee named before the incoming 2009 freshman class is sworn in on Jan. 3rd would have more seniority. And if Carney isn't the pick, then Delaware Secretary of State Harriet Smith Windsor could be the choice, observers say. She's in her late 60s, a loyal ally of Gov. Minner, and unlikely to want a long career in the US Senate. If selected, she'd be the first female US senator from Delaware.