This week, Maryland Republican gubernatorial nominee Larry Hogan became the first general election candidate in 20 years to opt to participate in the state’s public financing system. He could very well be the last for quite some time.

That’s because the Fair Campaign Financing Fund — from which Hogan is getting a grant of about $2.6 million — is about to run out of money. And as of now, state leaders have no plans to replenish it.

The fund, created by the legislature four decades ago, was built up through a voluntary add-on on Maryland income tax returns. Interested taxpayers could check a box and contribute up to $500 a year.

But in 2010, lawmakers voted to remove the add-on because the fund had been tapped only once: in the 1994 governor’s race. And on a few occasions, lawmakers had used money sitting in the fund to pay for other election-related costs.

The way the system was set up, gubernatorial candidates who participate get money from the state in exchange for agreeing to limit their overall spending. Over the years, many candidates calculated that the cap was too low for them to compete.

The 2014 gubernatorial race brought a flood of renewed interest, however, starting with Del. Heather R. Mizeur (D-Montgomery). She touted her use of the fund as consistent with the grass-roots Democratic primary campaign she wanted to run.

(Mizeur wound up finishing third in the primary, behind Lt. Gov. Anthony G. Brown and Attorney General Douglas F. Gansler.)

Hogan, who made a relatively late entry into the Republican field, also decided to use the public financing system in the primary. Two of his GOP rivals — Harford County Executive David R. Craig and Del. Ronald A. George (Anne Arundel) — expressed interest as well. But Craig and George failed to gain access to public matching funds because they could not raise about $260,000 in required “seed money” from individual donors in increments of $250 or less.

During the primaries, Mizeur qualified for more than $780,000 in public matching funds, according to elections officials. Hogan qualified for about $330,000.

For the general election, the rules are different: Hogan is simply given a grant of about another $2.6 million to run his campaign. No seed money is required.

After Hogan is paid, the Fair Campaign Financing Fund will only have about $1 million left. The only revenue coming into the fund these days is the interest it earns.

If lawmakers don’t act to replenish the fund, Maryland will have an unworkable law.

“Basically, we’ll have a law on the books without the ability to fund its operation,” said Jared DeMarinis, director of candidacy and campaign finance for the Maryland State Board of Elections.

During the last legislative session, Del. Eric G. Luedtke (D-Montgomery) introduced a bill to revive the add-on — but it went nowhere.

That was partly due to opposition from environmentalists. Maryland has three other add-on programs, including one that benefits the Chesapeake Bay. The environmentalists didn’t want any more competition.

Luedtke said he is going to take another stab at his bill when lawmakers return in January. But even if he is successful, it could be a long time before the fund is built back up.

The money raised from the add-on never exceed $200,000 a year prior to its repeal in 2010.

“That wouldn’t even begin to cover it,” Luedtke said, adding that lawmakers should be looking at other ways to fund the program and to expand it. Currently, only candidates running for governor are eligible.

The good news, Luedtke said, is that the use of the fund this year could provide some fresh momentum.

“It proves the system is still viable,” he said. “Everyone had thought the system was dead.”