An unlikeable and vulnerable incumbent with poll numbers in the tank and more unpopular decisions ahead. A wide-open field after the challenger City Hall feared most dropped out even before jumping in.

If ever there was an opening to take on Mayor Rahm Emanuel, this is it. Yet, the biggest name who’s even considering it is a fiery union president who has never before run for public office.

Why did County Board President Toni Preckwinkle take a pass? Why isn’t anybody else — either in the African-American community so alienated by Emanuel’s school closings, charter openings and school construction concentrated on the North Side or anywhere else — stepping up to take her place?

Politicians and political operatives interviewed Wednesday blame the same factors that were at play four years ago: Emanuel’s fund-raising prowess, his reputation for brute force politics while appeasing opponents and the intractable problems on the mayor’s desk.

“It speaks to the disturbing influence of money. You’ve got to have the resources to be viable,” said state Sen. Kwame Raoul (D-Chicago), among a long list of promising Chicago politicians to take himself out of the running.

“To what extent are we both nurturing and embracing a bench? That’s a valid question. Part of that will come back to the resource question. You can have bright stars and up-and-comers. But, without resources, they will always be just bright stars and up-and-comers.”

Raoul has been the Illinois General Assembly’s point-man on pension issues. He helped Emanuel win legislative approval for a Chicago pension reform bill — when Preckwinkle couldn’t —  after the mayor agreed to drop any reference to raising property taxes.

The senator acknowledged that Emanuel is vulnerable because of issues tied to both style and substance. That’s even with $8.3 million-and-growing in his campaign war chest and another $1 million-and- growing in the super-PAC created to re-elect the mayor and his City Council allies.

But, after flirting with races for Illinois attorney general and governor, Raoul said, “My focus has been elsewhere. From a practical standpoint, it would be ill-advised to enter into something like that.”

U.S. Rep. Luis Gutierrez (D-Chicago) has long coveted the mayor’s job and flirted with the idea of challenging former Mayor Richard M. Daley in 2007 before endorsing Daley.

Gutierrez would be a prime candidate to capitalize on Emanuel’s dismal poll numbers among Hispanics.

During Emanuel’s days as White House chief of staff, Gutierrez accused Emanuel of standing in the way of immigration reform and being singularly responsible for President Barack Obama’s failure to deliver on his campaign promise to Hispanics.

Gutierrez retaliated by endorsing mayoral candidate Gery Chico over Emanuel.

But, you can scratch Gutierrez name off the list of potential challengers. He’s agreed to co-chair Emanuel’s re-election campaign, thanks, in large part, to the mayor’s decision to join Gutierrez as a champion of immigration reform.  

Chico finished second to Emanuel in 2011 with 23.9 percent of the vote. But sources said he is not considering another race for mayor.

Cook County Sheriff Tom Dart flirted with the idea of running for mayor in 2011, only to stun his supporters by dropping out, arguing that the job would require him to be “less of a father” to his five young children.

Four years later, nothing has changed.

“On the weekends, I’m a full-time dad, and I like it that way,” Dart said Wednesday.

“When my kids get a little older, then my world will open up. But, I still have one who just turned five and I have a six-year-old. There are certain things I’m not gonna give up because of politics.”

Illinois Attorney General Lisa Madigan has a $4.8 million campaign war chest filled with cash raised while she flirted with running for governor. She dropped out after concluding that “the state would not be well served by having a governor and speaker of the House from the same family.”

Scratch her name off the list, too. She’s not even considering it.

Ald. Edward M. Burke (14th) has nearly $4 million in the three political funds under his control.

But, the City Council’s 70-year-old dean is recovering from prostate cancer surgery and is highly unlikely to jeopardize the political peace he has made with Emanuel after the mayor blamed Burke for the residency challenge that nearly knocked Emanuel off the 2011 ballot.

That leaves Chicago Teachers Union President Karen Lewis as the strongest possible challenger to Emanuel.

But, a political operative who asked to remain anonymous questioned whether Lewis would actually enter the race after returning from a Hawaiian vacation.

“She might be positioning herself to do it to build leverage, then pass it off to the most viable candidate and go negotiate her [teachers] contract,” the operative said.

“My theory is she’s just leveraging. She tried to force Toni [Preckwinkle] to do it. But, it didn’t work.”

Preckwinkle was apparently so serious about challenging Emanuel, her advisers were fishing around for a campaign manager last month.

Although she has blamed her decision not to run on unfinished county business, speculation abounds that she was bullied out of the race by a mayor with a reputation for hardball who may have played a behind-the-scenes role in killing the county pension reform bill.

“If Toni ran for mayor, it was fully understood that Rahm would go negative on her. Campaigns are rough and tumble things. She understood that. She wasn’t scared off,” said Ken Snyder, Preckwinkle’s political consultant.

“She simply decided to focus on the work she still has to do.”