In a major escalation of the controversy surrounding Boston Mayor Michelle Wu’s defeated commercial tax hike plan, a Boston city councilor is asking the state Inspector General to step in and potentially investigate why Wu provided “outdated and inaccurate” tax assessing data to the council and state Legislature to try and win over elected officials.

“It is now clear that the Boston City Council previously voted on the administration’s property tax classification legislation based on inaccurate data provided to the body,” Councilor Ed Flynn wrote in an email to the IG late Tuesday.

“I believe it is necessary to look into how and why there are such discrepancies in the data that was provided by the Assessing Department to ensure that this confusion does not occur in the future. It is critical that Boston residents and their elected officials are informed with the most accurate data to make informed decisions on these matters.”

Flynn was the lone initial vote against Wu’s tax plan – which this week was held up and killed by the state Senate.

The state Senate Democratic leadership believed the tax hike was no longer necessary since the new data showed residential tax rates would not be raised as high as Wu first claimed.

One Boston senator, Nick Collins, accused Wu of leading a campaign of “fear” to get legislators and councilors to approve her home rule petition to raise commercial tax rates.

The dispute has caused a major rift between Wu and top Democratic legislators and has deeply hurt the Boston mayor’s credibility as she heads into her reelection campaign.

Flynn, the former council president, had been one of the few voices against Wu’s home rule petition until the new assessing data became released and incensed some lawmakers.

Some lawmakers said they would not approve Wu’s petition until she looked at her own budget first for potential cuts – a demand she has refused to agree to.

Flynn said in the email to Inspector General Jeffrey Shapiro that he has “concerns regarding the City of Boston’s real estate assessment projections.”

He asked Shapiro for a “determination whether an investigation is warranted” into the home rule petition tax controversy.

A spokesperson for Shapiro could not be immediately reached for comment Monday night.

Flynn’s request for an investigation escalates the political feud between him and the mayor to new levels.

Flynn is among those considering whether to challenge Wu next year, and has amassed a campaign war chest of nearly $1 million. Another potential candidate is Josh Kraft, son of New England Patriots owner Robert Kraft.

Wu’s weakened political standing due to the tax controversy could prompt Kraft and possibly others to get into the mayor’s race.