City Councillor At-Large John Connolly yesterday acknowledged what has been apparent to close observers of campaign finance filings: He is considering a run for mayor this year regardless of what Mayor Thomas Menino decides to do.

“I’m actively starting to call supporters and opinion leaders,” said Connolly, who has been on a fundraising tear in the last few months. According to the Office of Campaign and Political Finance’s website, he has raised $103,969 in 2013, and has an ending balance in his campaign account of over $300,000.

Menino, who has been recovering from a variety of ailments through regular physical therapy and a convalescence at the city-owned Parkman House, has significantly slowed his fundraising pace. His campaign filings show he has raised $3,350 this year, and he has roughly $300,000 more in the bank than Connolly.

Connolly’s consideration of a mayoral run was first reported by the Boston Globe and the Herald on Tuesday night. Menino has not said whether he’s running for a sixth four-year, and often plays coy with reporters when they ask.

“This for me is about my belief that it’s time for new energy and new ideas, and that Boston is so full of talent,” Connolly said.

A West Roxbury resident who grew up in Roslindale and was elected to the 13-member council in 2007, Connolly said he is eyeing a possible $1 million budget for a mayoral campaign. “There’s no doubt if we’re in this race we’re going to have to run a guerrilla-style campaign,” he said.

As chair of the City Council’s Education Committee, Connolly has emerged as a top critic of the Menino administration. In July, he called for Superintendent Carol Johnson’s resignation after she declined to discipline a headmaster after learning he was arrested on a domestic assault charge. The headmaster later resigned and Johnson said she regretted her lack of action.

Connolly, a former middle school teacher, would be up against history if he faces off against Menino, who has dusted off any and all opponents since 1993, including former City Councillor At-Large Michael Flaherty against whom he took 57 percent of the vote in 2009.

“Every race is different,” Connolly said.

Two candidates, both of them longshots, have already declared that they are in mayoral campaign mode: Hyde Park’s Will Dorcena and Fields Corner’s Charles Clemons.