Pittsburgh Mayor Luke Ravenstahl takes questions Friday during a news conference where he announced he has abandoned his bid to seek re-election. Ravenstahl cited the “grueling demands” of the job on his family and friends.

PITTSBURGH — Luke Ravenstahl, Pittsburgh’s youngest mayor, won’t seek re-election after deciding the burdens of the job were too much to bear for himself, his family and friends.

Ravenstahl, who became mayor at 26, said Friday he would serve out his term, but blamed the “grueling demands” of the job as he discounted suspicions that an ongoing federal investigation of the police force played a role.

Instead, he said that he had accomplished a dream and was ready to move on.

“I’ve done nothing wrong, and that will be proven over time,” he said, sounding relieved, calm and confident of his decision.

Ravenstahl took dozens of questions from reporters, but had no answer for one: Exactly what caused him to withdraw from the race just 10 days after he declared his candidacy?

Ravenstahl said his doubts began two years ago. His seven-year marriage to a high school sweetheart ended in 2011, and at the time, Ravenstahl said his wife was uncomfortable with his political career and the limelight.

He is also in the midst of a federal investigation of city police business that led him to ask for the resignation of the city’s police chief.

Ravenstahl said he’s not a target of the FBI probe, which is believed to center on a fund the police bureau kept for fees that bars and other businesses paid the city for using its off-duty police officers as security guards. That money was then spent on city activities, including expense accounts for the mayor’s bodyguards.

The rigors of denying wrongdoing in the wake of such reports, he said, also played a role in his decision because he and his staff were “spending more time doing things or responding to things that are simply false, that are harmful and hurtful,” than on city business.

“It’s something that is the nature of the business, but something that, you know, clearly is what I guess I enjoy the least about the business,” Ravenstahl said.

The mayor also said reports that his mother’s health led to his decision -were untrue, gesturing to his left where she stood without detailing those problems.

“Also as you can see, my mom is great, she looks amazing. ... She does have some medical issues that she is dealing with, but I am confident that she will overcome and defeat them,” he said.

A number of supporters expressed surprise and regret.

“It’s shocking to a lot of people,” said Darrin Kelly, a trustee of the city firefighters union. “At the end of the day if he feels that’s the best thing for him, we wish him the best of luck. I truly believe that he’s done amazing things for this city.”

Ravenstahl said party leaders didn’t pressure him.