THE REMOVAL OF Sen. Sonia Chang-Diaz as co-chair of the Legislature’s Joint Committee on Education drew harsh words on Thursday from leaders of four organizations serving communities of color, who charged that the move weakens advocacy for vulnerable students and waters down the already limited clout minority lawmakers wield on Beacon Hill.

A statement issued by six women minority leaders said the decision last week by Senate President Karen Spilka to oust Chang-Diaz from her post was particularly concerning as the Legislature prepares to consider major reform of the state’s school funding formula.

“By removing the most visible and vocal supporter for communities of color from this Committee, we are left without an advocate who will champion the issues that impact our most vulnerable children during one of the most important education equity decisions of our time,” said the statement.

Spilka said the change in no way signals a weakening of the Senate commitment to underserved children, and she cited her own background as a social worker and school committee member who first raised the need to revamp the state’s school funding formula two decades ago.

“This has been part of the fabric of my being as a state legislator,” said Spilka, who restated her resolve to reach agreement on a new funding plan after lawmakers failed to do so last year.

Chang-Diaz, a Jamaica Plain Democrat who served for eight years in the Senate’s top education post, was reassigned to chair two other committees just as the Legislature prepares to tackle the biggest overhaul of education funding since the 1993 Education Reform Act. The move also came only weeks after she unveiled an ambitious funding bill that Chang-Diaz said could add $900 million to $2 billion to state education aid.

She is the only Democratic minority member of the 40-person Senate, and the leaders issuing the statement today said Chang-Diaz’s removal as Senate education chair “raises serious concerns about the state Legislature’s commitment to our children, particularly English language learners, children from low-income families, and children of color.”

The statement came from Alex Oliver-Davila and Vanessa Calderon-Rosado, co-chairs of the Greater Boston Latino Network; Betty Francisco and Eneida Roman, cofounders of Amplify Latinx; Diana Hwang of the Asian American Women’s Political Initiative; and Tanisha Sullivan, president of the Boston NAACP.

Sullivan said in an interview that the move raises “a concern that those children in particular are going to lose out in any negotiation that has to do with education reform in this session.”

Chang-Diaz’s office said she was out of state with her family and not available for comment.

“I’m not going anywhere,” she said last week in a Twitter message to advocates about the upcoming education funding debate. “I’ll be here, fighting alongside you every step of the way until we get it done right for all our kids, including & especially low-income kids & kids of color who can’t be shortchanged again.”

Chang-Diaz was part of a House-Senate conference committee that could not reach agreement on funding reform in the closing days of the Legislature’s formal sessions last year. She sharply criticized House leaders over the failure to strike a deal.

There had long been tension between Chang-Diaz and her counterpart, Rep. Alice Peisch of Wellesley, the House co-chair of the Education Committee.

In naming Sen. Jason Lewis to replace Chang-Diaz as the Senate co-chair of the committee, Spilka suggested his approach to difficult issues might be what’s needed to reach agreement this session on education funding.

“Fresh perspective, fresh approach, and a passion for this issue,” Spilka said in describing what he’ll bring to the table. “And Sen. Lewis did do a great job with the grand bargain,” she said, referring to an agreement Lewis helped broker last year on a set of economic issues, including the minimum wage and paid family leave. “Nobody thought that was going to be successful, and he was able to close the deal.”

The six minority leaders took issue with the idea that Chang-Diaz has been too forceful or not pragmatic enough to lead the funding negotiations. “From our perspective, it is important when advocating for some of our most vulnerable children that we are resolute in that advocacy,” Sullivan said.

Lewis, a Winchester Democrat, was an early cosponsor of Chang-Diaz’s education bill and said he shares her commitment to reset the state’s school funding formula, a conversation set in motion by a 2015 commission that identified significant funding gaps in meeting education needs.

The six women minority leaders also expressed concern that Legislature’s education co-chairs now “represent predominantly white and affluent suburban districts.”

The education committee includes three minority House members.

The controversy over Chang-Diaz’s ouster has deflected attention from changes in the House leadership positions that saw two white men named to top positions held last term by minority legislators.

Byron Rushing, a veteran black lawmaker from the South End who served as House assistant majority leader, and Jeffrey Sanchez, a Hispanic state rep from Jamaica Plain who served as chairman of the House Ways and Means Committee, both lost their seats to primary challengers last September.  Their slots were filled by Rep. Joseph Wagner, who was named assistant majority leader, and Rep. Aaron Michlewitz, who now chairs the House budget-writing committee.

The statement by Sullivan and other minority leaders said they were concerned about the overall lack of diversity in top positions on Beacon Hill and elsewhere.

They said Chang-Diaz was only “the latest example of how people of color – especially women of color – are subject to rebuke for representing us too fiercely and too well.” Sullivan pointed to the treatment of former University of Massachusetts Boston chancellor Keith Motley by university officials and Boston state Rep. Russell Holmes, who has tangled with House leaders, as other examples.

They also decried the overall paucity of minority members in the Legislature.

“I very much appreciate the issues that they raise,” said Spilka. “Their concerns are my concerns as well in terms of people of color being underrepresented in the Legislature in general.”