The chief of staff to Ottawa Mayor Larry O'Brien has announced he is about to resign.

Walter Robinson, who is just six months into his two-year contract, said he plans to leave the job at the end of July.

Walter Robinson said he agrees with what the mayor wants to accomplish, but has disagreed with O'Brien about how to accomplish it.
(CBC)

Both Robinson and O'Brien cited differences of opinion as a factor in the "mutual" decision.

"Larry has a very focused business background that I'm not used to," Robinson told reporters on Wednesday.

He added that the mayor's agenda has now moved into the implementation stage. 

"I totally agree and fully support his agenda going forward in what he wants to do … We've had some disagreements on the how, not the what," he said.

The skill set needed to help the mayor at this stage is different from the one he himself has developed in 20 years of mainly political work, he added.

'The reality is the team that the mayor brought in to accomplish his objective just lost one of its star players.'— Coun. Alex Cullen

Robinson is the former head of the Canadian Taxpayers Federation, a group that lobbies for reduced taxes and accountability in government. O'Brien hired him in November, two weeks after being elected mayor on a promise to freeze taxes for four years. 

In response to reporters' questions, Robinson said his resignation has nothing to do with an ongoing Ontario Provincial Police investigation into bribery accusations against O'Brien, and that he was not pushed out.

Mayor hopes to stay friends

O'Brien said he was announcing Robinson's resignation "with a sad heart." 

"I think Walter feels that he's accomplished quite a bit and think he's off to other challenges," said O'Brien, who told reporters that differences of opinion are bound to happen "when you have two alpha males in the office." 

He added he hopes to maintain his friendship with Robinson.

Councillors said they were shocked by Robinson's departure and didn't see it coming.

Coun. Alex Cullen said the event does not bode well for the mayor's agenda.

"The reality is the team that the mayor brought in to accomplish his objective just lost one of its star players," he said.