With Mayor Ed Murray’s announcement Tuesday that he isn't running for reelection, the race to replace him is now wide open with additional candidates considering entering an already crowded race.

Former U.S. Attorney Jenny Durkan is expected to announce in coming days, according to an advisor close to Durkan.

State Senator David Frockt and State Representative Jessyn Farrell also confirmed that they’re considering running for mayor.

State Senator Bob Hasegawa is the latest candidate to officially jump in, adding his name to a list of nearly a dozen candidates who had previously filed, including former Seattle Mayor Mike McGinn, urban planner Cary Moon and attorney and organizer Nikkita Oliver.

“I think it's going to be wide open for awhile, and it's probably going to be quite competitive,” said local labor leader David Rolf, president of SEIU 775.

Murray had already locked up a long list of labor endorsements that are now up for grabs. Rolf believes some unions may wait until after the primary to officially back a candidate.

“It’s an exceptionally large field with a lot of progressive candidates in it,” said Rolf.

Hasegawa, a Bernie Sanders delegate and longtime labor organizer, believes his labor background could give him an edge.

“It's too soon to tell,” said Rolf. “There are several other legislators whose names have been tossed around who all have very strong labor voting records. We have a U.S. Attorney who put herself through college as a teamster whose name is floating around.”

Rolf is referencing Durkan who is likely to become the establishment candidate, if she enters the race.

“We’re very excited Jenny is considering running,” said Maud Daudon, president of the Seattle Metropolitan Chamber of Commerce.

Will the Chamber back Durkan?

“We have been in discussions with a lot of potential candidates,” she continued.

The Chamber’s powerful political action committee, CASE, plans to formally evaluate candidates in coming weeks ahead of the August primary.

“We’ll be looking for a candidate who actually reflects the values of our chamber members, which is basically a strong focus on our economy and business climate, which is critical to the region, and also a focus on the quality of life here and not leaving people behind in this community,” said Daudon.

“We see elements in some of the candidates, but we’re probably going to be looking for a candidate who possesses all three of those qualities in large and visible ways, and we’re optimistic that such a person will emerge,” Daudon said of the current field of candidates.

As for what happens to Murray's surplus fundraising dollars and campaign infrastructure, it's too early to know.

"A lot of the staff might go work for other campaigns, or they might do something else," said longtime Seattle political consultant Christian Sinderman, who had worked on Murray's campaign. "And for the endorsing organizations, they’ll take a look at the candidates as they emerge over the next several days and decide where they’re going to go, but there’s a lot of uncertainty."

"While this is an incredibly sad day, it does give this mayor an opportunity to close out his term with the same kind of energy and class that he’s brought to it this far, and for new candidates to emerge that can hopefully carry on the legacy that he’s presented here today," Sinderman continued.