Maryland Lt. Governor Anthony Brown as he kicked off his campaign for governor in May. (AP Photo/Jose Luis Magana)

Maryland Democratic gubernatorial hopeful Anthony G. Brown won the endorsement Saturday of the state’s largest teachers lobby after pledging that the group would be “a full partner” with his administration on education issues.

The Maryland State Education Association (MSEA) became the latest player in state politics to side with Brown, Maryland’s lieutenant governor, in a competitive Democratic primary next year that also includes Attorney General Douglas F. Gansler (D) and Del. Heather R. Mizeur (D-Montgomery).

Both Gansler and Mizeur — as well as Republican hopeful David R. Craig, the Harford County executive — had actively courted the group, which claims 70,000 educators and other school employees as members and was gathered for an annual convention in Ocean City.

“Anthony Brown is the champion our students need to continue to move Maryland’s schools forward,” MSEA President Betty Weller said in a statement after a vote Saturday by the group’s representative assembly to endorse Brown, who is seeking to succeed Gov. Martin O’Malley (D).

In a speech to the convention Friday, Brown said MSEA would have “the loudest voice when it comes to education issues in the state of Maryland” and cited his work with O’Malley, a stretch during which the state’s schools have been ranked No. 1 by Education Week magazine for five years in a row.

Brown also voiced support for several of the organization’s priorities, including boosting annual state spending on public school construction to at least $500 million. Under O’Malley, outlays have averaged about $340 million, far more than under his predecessor.

Addressing the convention Friday, Weller predicted that the candidate endorsed by her organization would win, “because we will out-organize, out-mobilize and outwork anyone else.” She added, “It would be foolish to underestimate the power of our members to put their time, money and passion into supporting friends of public education.”

Under MSEA rules, the assembly on Saturday considered a recommendation reached Friday by its endorsement council to endorse Brown. That motion needed the support of 58 percent of those voting to pass. An MSEA staff member said it received 71 percent approval.

Since declaring his candidacy in May, Brown has racked up far more endorsements than his rivals, both from prominent Democrats and from interest groups that traditionally play a role in Democratic primaries.

Besides O’Malley, those endorsing Brown have included Sen. Barbara A. Mikulski (D-Md.), House Minority Whip Steny H. Hoyer (D-Md.), state Senate President Thomas V. Mike Miller Jr. (D-Calvert) and House Speaker Michael E. Busch (D-Anne Arundel). Some other labor groups, including the local chapter of the Service Employees International Union, have also lined up behind Brown.

Gansler, who has been widely regarded as Brown’s chief rival in the early stages of the 2014 race, has sought to play down the significance of Brown’s endorsements and to position himself as the anti-establishment candidate running against a Democrat “machine” — a term he used in an address to the teachers on Friday.

But Gansler, Mizeur and Craig all pursued the backing of the teachers union, a process that included Friday’s speeches, as well as responding to a 30-page questionnaire and sitting for one-on-one interviews with Weller that were recorded and made available on YouTube.

In his speech, Gansler proposed exempting teachers’ retirement income from taxation, saying he considered teachers to be “local heroes,” along with military veterans and first responders. A campaign aide later clarified that Gansler was still developing a proposal and that it probably would not be a full exemption.

Brown told reporters after the speeches Friday that such a measure would be very costly and that it was not something teachers were seeking. The lengthy MSEA questionnaire did not include a question about that issue, Brown noted.

All three Democratic candidates have developed proposals to expand access to pre-kindergarten programs, an issue they pushed in Friday’s speeches. Mizeur has developed the most aggressive plan, which would make full-day pre-K available to all 4-year-olds and part-day programs available to 3-year-olds in families that have lower incomes.

Craig has said the state should not let spending on pre-K programs detract from its commitment to K-12 funding.

In his remarks, Craig also stressed his previous work as a classroom teacher for 15 years.

“I know your challenges,” Craig said. “I’ve walked in your shoes. I have the chalk on my hands.”

Two other Republican candidates running for governor — Del. Ronald A. George (R-Anne Arundel) and Charles County businessman Charles Lollar — did not take part in the endorsement process.