Portland Mayor Charlie Hales is dropping his bid for re-election.

Hales' unexpected decision to abandon a re-election campaign for 2016 opens a clear path to City Hall for Oregon Treasurer Ted Wheeler, who announced in September he would challenge Hales.

Hales never formally filed paperwork to run for a second term, but told media since the spring that he was running. "As you know," Hales wrote in a Sept. 18 email to WW, "I have not yet filed for re-election, although I will later in the fall."

Hales announced his plan in a press release Monday afternoon after WW published its story, saying he couldn't run for re-election and govern the city simultaneously.

"I cannot do both of these tasks faithfully and well," he wrote in the statement.

Yet Hales was burdened by a number of problems that would have dragged down his campaign.

"This is a bad time to be an incumbent—for anybody," says Len Bergstein, a veteran campaign consultant. "And it's been a really bumping road for this particular incumbent."

Hales' chief political consultant, Mark Wiener, took a job as a lobbyist for ride-sharing giant Uber in December 2014 and then aided in Uber's loosening of city rules so it could operate legally in Portland. Wheeler pointed to the setup at his campaign announcement and accused Hales of fostering backroom deals.

Hales' ties to real-estate developers also hurt him.

For example, WW recently raised questions about undisclosed gifts to Nancy Hales' program at Portland State University. The mayor's wife runs an organization that brings visiting delegations to Portland to study the city's urban infrastructure. Financial supporters of Nancy Hales' First Stop Portland include some of the mayor's biggest campaign contributors in real-estate development, further fueling public perception that Hales was beholden to real-estate interests at a time when Portland's rents are rising sharply and many voters are fed up with the city's growth.

Fundraising, it seems, wasn't one of Hales' problems. At least not yet.

Hales has reported raising $143,000 in 2015, according to state records. That includes contributions made as recently as Oct. 21.

Wheeler, having announced his bid only last month, has reported raising $106,000.

On Oct. 16, Wheeler scored a campaign coup, announcing that former mayors Vera Katz, Tom Potter and Sam Adams were all endorsing Wheeler. The news surprised many because Katz endorsed Hales in 2012 and Wheeler sparred with Adams when Wheeler was chairman of Multnomah County. In 2009, Wheeler announced he supported the petition campaign seeking Adams' recall in the wake of the Beau Breedlove scandal.

Hales' exit follows a path similar to Adams', who announced in 2011 that he wouldn't run again because of the dual demands of campaigning and running the city. He also factored in a poll that showed he'd face a tough race. "I have fire in the belly [to run again]," Adams told WW. "But the tradeoff is, I wouldn't devote the necessary time and attention to being mayor."

Hales doesn't appear content to let Wheeler walk into office.

"The filing deadline is still over four months away, and I hope and expect that several qualified candidates will seek the office of mayor," he wrote in his Monday announcement. "There are some dynamic new leaders in our community, and I'm excited to see who steps up."