City Councillor At-Large Michael Flaherty this week officially announced his intention to topple Mayor Thomas Menino.

In a video posted on the popular website YouTube and a letter sent to supporters, Flaherty called for change in the mayor's office.

Menino, who has held the slot for the last 15 years, is widely expected to run for another term, but has yet to make an announcement. Menino has said he is focused on the budget.

Kevin McCrea, a Boston businessman, announced last week in Dorchester that he was in the race. Councillor At-Large Sam Yoon, whose district includes Dorchester, is widely expected to mount his own run.

"I assure you, this campaign will be about the bottom up - not the top down - and will engage all residents to find what is keeping them up at night and where they see the city's greatest potentials," Flaherty said in his letter. "This campaign will be fueled by your ideas and will be committed to replacing out-of-touch politics with policies that meet the specific needs and priorities of you and all Boston residents."

Flaherty supporters said the an eight-year veteran of the City Council would be a "breath of fresh air."

"He's a tried and true guy, politically and personally," said Ed Proctor, a Dorchester native. "A lot of people in Dorchester consider him more of a friend than a politician."

Proctor acknowledged Menino's high approval ratings. "It's going to be a uphill battle for him, but I think he can pull it off," he said.

A South Boston resident, Flaherty has been meeting with campaign aides in recent weeks and made mock-ups of a mayoral campaign logo.

Up against Menino's solid $1.3 million campaign war chest, Flaherty has also been fundraising at a rapid clip, pulling in $4,375 this week. Flaherty has about $600,000 in his campaign account.

Flaherty is a former assistant district attorney and City Council president.

He was first elected in 1997.

More on Michael Flaherty's campaign can be found at his website.