Maryland Del. Heather Mizeur is seen during an event announcing her running mate, Delman Coates, on Nov. 13. (Karl Merton Ferron/Baltimore Sun)

Maryland Democratic gubernatorial hopeful Heather R. Mizeur said Tuesday that she will participate in the state’s public-financing system next year, becoming the first candidate in 20 years to agree to limit overall spending in exchange for matching funds.

Mizeur, a Montgomery County delegate who faces two better-known opponents in June’s primary, said her decision was consistent with a desire to run a grass-roots campaign at a time when corporate money is playing an outsize role at all levels of politics.

“I refuse to accept the only way to win this race is to become part of the problem,” Mizeur said in an interview.

“We should be restoring the public trust in our system. . . . We should make sure the voters’ voices are the ones that get heard in this process.”

But some people suggested that Mizeur was motivated by being greatly outpaced in fundraising by Lt. Gov. Anthony G. Brown and Attorney General Douglas F. Gansler, who have greater name recognition. Under Maryland’s public-financing system, Mizeur could qualify for more than $1 million in state funds next year if she agrees not to spend more than roughly $2.5 million on her primary campaign.

Although Brown and Gansler are expected to spend millions of dollars more than that, Mizeur would have enough money to make her voice heard.

“It may be a principled matter, but it’s also making a virtue out of a necessity,” said Donald F. Norris, chairman of the public policy department at the University of Maryland Baltimore County. “It’s very unlikely, given that she’s a dark-horse candidate, that she could raise serious money on her own.”

On Wednesday, Mizeur plans to formally unveil several campaign finance reform proposals, including banning corporate contributions and expanding Maryland’s public-financing system to candidates for other state offices.

She disputed the notion that accepting public funds would boost the money she would have for the race, saying she could have raised more on her own.

Mizeur’s announcement is the latest in a series of moves that have reinforced her status as the most liberal candidate in the race. She previously proposed legalizing marijuana, expanding subsidized pre-kindergarten and raising the minimum wage to $16.70 by 2022.

The last time candidates for governor in Maryland accepted public money was in 1994, when two Democrats and a Republican agreed to the terms of the system.

The money helped the Republican, Ellen R. Sauerbrey, prevail against the front-runner in the GOP primary. And in the general election, Sauerbrey nearly defeated Democrat Parris N. Glendening, who did not agree to the spending cap and greatly outspent her.

Since then, Maryland’s public-financing system has been shunned by gubernatorial candidates from both parties, in large part because the spending limit is now “at a very low level” compared with what top-tier candidates are capable of raising otherwise, said Jennifer Bevan-Dangel, executive director of Common Cause Maryland, which supports public financing.

In 2010, Gov. Martin O’Malley (D) and former governor Robert L. Ehrlich Jr. (R) collectively spent about $22 million on their rematch.

It has been nearly a year since the 2014 hopefuls were required to disclose their finances, so it’s impossible to know exactly where the money chase stands.

As of January, however, Gansler already had more than $5 million in the bank. Brown reported having $1.6 million — a figure later bolstered by his choice of a running mate: Howard county executive Ken Ulman had roughly $2.1 million in his campaign account before joining Brown’s ticket.

Mizeur had about $380,000.

Candidates must raise seed money in increments of $250 or less from individuals to qualify for Maryland’s public-financing system. Once candidates meet a certain threshold — expected to be about $250,000 next year — they become eligible for matching funds.

The exact cap on spending for the primary is determined by a formula based on the state’s population and inflation. Elections officials won’t make a final calculation before January.

Candidates who win the primaries can also become eligible for a state grant for the general election. Next year, the size of the grant is expected to be approximately $2.5 million.

Under changes that Mizeur will propose Wednesday, the state would continue to provide matching funds for contributions of $250 or less, with a maximum match of $4 million. After that, candidates could keep raising money in the same increments, but they would receive no additional matching funds.

Mizeur would also allow candidates for other statewide offices, including attorney general and comptroller, to participate in the public-financing system. The system would also be open to candidates for the House and Senate.

Mizeur will also propose banning corporate contributions as well as contributions from those who bid for state contracts. She would also expand a “cooling off” period for former legislators who want to become lobbyists, changing the rule from one legislative session to two calendar years.