Plenty of names have been bandied about since Persson's resignation on election night.
But just when it seemed that Margot Wallström and Carin Jämtin would battle it out on the final straight, both of them dropped out.
Mona Sahlin, a colourful former government minister, is now the name on everybody's lips.
But has the party really decided that the leader must be a woman? If so, are there any other female candidates left? Or is their a male heir apparent waiting in the wings?
The Local spoke to political scientist and social democratic commentator Stig-Björn Ljunggren to see if he could shine a light on the dark arts of the party nominating committee.
First things first: Mona Sahlin is being tipped as a dead certainty to get the nomination. Is she?
"Yes. It's what I've been saying all along. Some other candidates got a big boost in the media but it was more like choosing a Lucia than a reflection of reality," said Ljunggren.
Carin Jämtin is a case in point. Newspaper Aftonbladet made the 42-year-old Stockholm politician its leading candidate when it became increasingly clear that Margot Wallström was not interested.
"She was like a Lucia - the virgin who just came through the door, leaving no dirt on the floor. She is not ready for the job yet but she could be good material for the future," said Ljunggren.
While the Swedish media were looking for a Lucia, Ljunggren reckons the party was searching for a new Anna Lindh.
The former foreign minister - "a cross between my mother and Olof Palme" - was widely tipped to succeed Persson before her brutal murder at a Stockholm department store in 2003.
"Margot Wallström is somebody who's about the same as Anna Lindh. She knows this. And a lot of people in the party were serious about Wallström.
"But she was never comfortable in government, and she is happy where she is at the EU Commission," said Ljunggren.
If history is to be believed, a "no" in the Social Democratic nomination procedure is not always definitive. But Wallström and Jämtin have managed to convince commentators that they really are out of contention, which many feel has put former infrastructure minister Ulrica Messing, 38, back in the picture.
"If Sahlin falls out of the race for any reason then they may try with Messing again.
"She has been around for a long time but does not have very much power in the party.
"Many may feel that she's not ready, which is indicated by the fact that not even her own party district has pushed for her nomination," said Ljunggren.
Effectively then, Sahlin would seem to have the female side sewn up. But are there any male candidates skulking about? Former justice minister Thomas Bodström for example?
"Bodström was recruited just a few years ago. He has no background in the party.
"He needs to get out to the local branches and drink the beer and eat the 'pyttipanna'."
Swedish diced meat and potato dishes aside, is there any future in the former footballer?
"If we had to choose a perfect candidate it would be him with five more years of education in the party," said Ljunggren.
But in Ljunggren's view there are two long-serving male politicians ready to serve if called upon to lead the party into the 2010 election. Former finance minister Per Nuder is one. Former industry minister Thomas Östros is the other.
"There are a lot of people very much against Nuder.
"I've heard people say that they will leave the party if he's elected, or that he makes them puke.
"I don't really understand it. He's capable, he has been around, he's intelligent and he knows all there is to know about the political situation at home and abroad.
"But he was close to Göran Persson and a lot of party members think that Persson's gang must go," said Ljunggren.
Many observers have ruled out Thomas Östros on the grounds that he lacks charisma. Is that a fair assessment?
"I don't think he minds being called boring. It gives him the element of surprise.
"And it's not necessarily a bad thing to be seen as somewhat buttoned-down - not so much the funny guy but definitely capable," said Ljunggren.
In his view then, the committee has three relatively strong candidates to choose between: Sahlin, Nuder and Östros, all of whom tread a "middle-of-the-road" political line.
"The nominating committee certainly doesn't want to interview socialists," said Ljunggren.
Mona Sahlin will be 50 this March, which, coincidentally, is also the month when the party congress makes its final decision.
She has still not completely shaken off the memory of the so-called "Toblerone affair" of 1996, when she was found to have paid for goods and services with her work credit card.
This and other factors have meant that not everybody is happy at the prospect of Sahlin taking up the reins. But how strong is opposition to her potential candidacy within the party?
"Not that strong. She has held things together after ten years of bombing in the media and the party.
"Some criticisms of her of are true. She is lazy, doesn't read enough documents, is not academic, and maybe takes too many chances. But she is also street smart."
Is it not a worry for the party that her checkered history will come back to haunt her?
"The scandals will come back to the surface before she is elected. But she is always watched closely anyway.
"It's like old alcoholics who start going to the pub again, you don't expect them to order a glass of milk," said Ljunggren.