Since Rahm Emanuel arrived in Chicago a few weeks ago, the once-long list of possible mayoral candidates in Chicago has dwindled. It seems the most viable, well-liked locals who seemed very sure about running have decided not to.

On Wednesday, after weeks of making very obvious moves toward a mayoral run, Cook County Sheriff Tom Dart announced at a press conference that he would not run for Mayor of Chicago.

The Chicago Sun-Times reports that Dart "didn't think it was right to run for mayor without leaving his elected post of sheriff," even though he has already hired a political consultant and even made a video teasing Rahm Emanuel.

"I have found it impossible for it to be compatible between running for mayor and being a father and husband," Dart said at a Wednesday news conference, according to the Chicago Tribune. (Scroll down for video of the announcement.)

Dart was considered by many to be Emanuel's main competition in the race for Chicago mayor.

The Daily Beast's Dirk Johnson summed it up accurately:

As the Cook County Sheriff, Dart, 48, has cultivated uncommon political street cred among Chicago's typically fractious blocs: liberal reformers, old Democratic Party machine loyalists, latte sippers along the lakefront, barber-shop customers on the South Side, and union hard-hats in the labor halls. "Tommy Dart is one hot political property," said Don Rose, a longtime political strategist. "He is clearly the main competition for Rahm Emanuel."

In a very early Chicago Sun-Times poll, Dart had more local support than Emanuel.

Dart said he had not talked to Emanuel about the decision. He said the only time the two had spoken was after bumping into each other in a restaurant. Asked if his decision would pave the way for an Emanuel victory, he said no.

"I don't believe I am paving the way for anybody," Dart said.

Dart has won national headlines with moves such as his lawsuit against Craigslist over adult content and his efforts to stop evictions of renters until banks make the process more humane.

Another high-profile candidate who bowed out of the race after collecting signatures is Rep. Luis Gutierrez. Gutierrez even attended the Mexican Independence Day Parade with dozens of volunteers wearing "Gutierrez for Mayor" shirts and carrying banners emblazoned with the phrase.

He announced that he would not run two weeks ago, saying that he wants to focus 100 percent on immigration reform in Washington.

So far, the Rahm Emanuel, former Chicago school board chief Gery Chico and city Clerk Miguel Del Valle are expected to run for mayor. The city council's black caucus is also expected to support a single "consensus" candidate. Those being considered include state Sen. James Meeks, former U.S. Sen. Carol Moseley Braun and Rep. Danny Davis. Check out our slideshow of remaining candidates here.

WATCH Dart's announcement here:

View more news videos at: http://www.nbcchicago.com/video.

Watch Dart answer questions about his decision here:

View more news videos at: http://www.nbcchicago.com/video.