Boston Zoning Commission Chair Michael Nichols, who heads a downtown advocacy group, said he plans to recuse himself from Wednesday’s vote on a contentious zoning plan that would clear the way for more skyscrapers downtown.

Nichols, president of the Downtown Boston Alliance, said that although he was cleared by the state Ethics Commission to take part in the vote, he ultimately opted not to weigh in on the zoning changes proposed in PLAN: Downtown in his official capacity as chair of the Zoning Commission.

“I was able to get a state ethics opinion that held that I do not actually have any conflicts tomorrow that run afoul of state law, but I nonetheless don’t want it to be a distraction — so I’m opting not to participate,” Nichols told the Herald Tuesday.

Nichols said he sought the ethics opinion based on a potential conflict of interest he may have in voting on the downtown zoning plan due to his advocacy group’s work to “analyze the plan for so long.”

He is the chair and president of the Downtown Boston Alliance, which represents commercial property owners in the city’s core.

Nichols said he is also planning to turn the gavel over to Commission Vice Chair Jill Hatton for the duration of the meeting that pertains to the downtown zoning plan. Ahead of the vote, a public hearing will be held.

The Downtown Boston Alliance submitted a letter in support of the plan — and its proposed creation of new skyline districts that would allow for 500-700 foot towers in parts of the historic downtown — to the Zoning Commission last Friday. It was sent by DBA Chief of Staff Kelsey Pramik.

“The plan’s passage today is critical for completing the neighborhood’s needed transformation such that it can align with a ‘new normal’ that requires a broader mix of uses, a modernized and more predictable zoning code, and a housing-first agenda to welcome a new generation of residents,” the DBA letter states.

The Alliance sent a similar letter of support to the Boston Planning and Development Agency Board last month, ahead of the board’s 4-1 vote in favor of the zoning plan.

If approved by the Zoning Commission, the Wu administration’s downtown plan would go into effect.

The plan would clear the way for new buildings to tower up to 700 feet over the historic downtown.

It has been a source of contention for other stakeholders, particularly the Downtown Boston Neighborhood Association, which has described the proposed changes as “destructive,” in that they would alter the character of the city’s core and turn it into Manhattan.

Critics have also flagged potential violations to the state’s shadow law, which was enacted in 1990 and restricts the creation of new shadows on the Boston Common and Public Garden at certain times of the day.

The Association supports additional towering in the Financial District east of Washington Street, where such heights have traditionally been allowed. It opposes new skyscrapers in the historic and increasingly residential Ladder Blocks and Park Plaza neighborhoods to the west of Washington Street and adjacent to the Boston Common.

The Celtics got some tips Monday at practice from an unlikely source in Tom Thibodeau, who helped eliminate them from the playoffs last season before he was fired as head coach of the New York Knicks.

Thibodeau led the Knicks to an appearance in the Eastern Conference Finals last season, but was fired after New York was swept in four games by the Indiana Pacers.

On Monday, he was at Celtics practice as a guest of head coach Joe Mazzulla.

“He’s obviously been one of the best coaches around for a long time. Worked here. Won a championship here. Just having him around makes me better, makes our organization better, so there’s a lot of respect for him,” Mazzulla said.

Thibodeau was an assistant coach in Boston for three seasons, starting with the team’s championship run in 2007-2008.

Last year, Thibodeau’s Knicks surprised many in basketball when they prevented the Celtics from earning a second straight title by eliminating Boston in the Eastern Conference Semifinals.

Celtics star Jaylen Brown told reporters that the time the team spent with Thibodeau at practice was valuable.

“We lost last year. It stung losing to the Knicks,” Brown said. “So to have Thibs here at our practice and explaining some of the things that he saw to help them beat us only helps me get better, only helps us get better. So I value that. Shoutout to Thibs for being here today.”

The Celtics open their season at home Wednesday against the Philadelphia 76ers. Boston then travels to take on Thibodeau’s former team at Madison Square Garden as the Celtics and Knicks play Friday night.