Former New York City Mayor Michael Bloomberg donated $2.5 million to the “Vote No on 2” campaign that opposes a ballot measure to remove the voting requirement. earning a high school diploma from MCAS in Massachusetts, according to campaign finance filings.

The donation was made last week, according to documents filed with the Office of Campaigns and Political Finance. website. This is the largest contribution to the “No to 2” campaign, less than a week before the elections.

Bloomberg’s donation is large enough to represent about half of the $4.8 million raised to date by the “No to 2” campaign.

In a statement to WBUR on Monday, a spokesperson for “Non sur 2” confirmed the billionaire businessman’s contribution.

“Mike Bloomberg has been a strong advocate for issues affecting children, such as reducing gun violence and improving education,” the spokesperson said. “We appreciate his support of our broad, bipartisan coalition of teachers, parents, educational and business organizations, and elected officials in opposition to Question 2.”

Max Page, president of the Massachusetts Teachers Association — the state teachers union leading support for Question 2 — said he learned of the donation Friday.

“I think Massachusetts voters are smart enough to listen to the thousands of educators who knocked on doors, made phone calls, and held up signs in support of Question 2, instead of a handful of billionaires who have long resisted progressive and positive changes for all of our students,” Page said Monday.

The union has so far invested nearly $12.7 million to support the initiative, mostly in-kind contributions, according to campaign finance reports.

Question 2 seeks to eliminate the state’s requirement that all public high school students in Massachusetts pass the 10th grade MCAS in English, math and science to graduate.

Before Bloomberg’s donation, the highest contribution to the No on 2 campaign was $250,000 made by New Balance Chairman Jim Davis earlier this month. Several other business and financial leaders donated $100,000 each. The ballot measure’s most vocal opponents include those in the business community and several top state officials, including Gov. Maura Healey and Secretary of Education. Patrick Tutwiler.