Attorney General Douglas F. Gansler. (Photo by Bill O'Leary/The Washington Post)

Trailing in the polls with less than two weeks until the primary, gubernatorial hopeful Douglas F. Gansler on Thursday proposed nearly $600 million in tax relief for the middle class, saying he wanted to offset some of the financial burden incurred under the administration of Gov. Martin O’Malley.

Gansler (D) said he would offer temporary tax credits of $200 a year for individuals and $400 a year for joint filers with annual incomes between $50,000 and $100,000. The tax relief would start in 2016 and run through 2018, costing the state treasury an estimated $194 million a year for those three years.

“The middle class is the heart and soul of the Maryland economy,” Gansler, the state’s attorney general, said in a statement. “Burdening these hard-working Marylanders with never-ending tax increases is not fair, and is not the answer to getting our economy moving again.”

He blamed Lt. Gov. Anthony G. Brown (D), who is leading Gansler by a 2-to-1 margin among likely Democratic voters, for the tax increases of recent years.

The primary is June 24. Early voting started Thursday.

“This sounds like a last-ditch scheme to grab some voters’ attention,” said Del. John L. Bohanan Jr. (D-St. Mary’s), a member of the House Appropriations Committee who has endorsed Brown. “If this was a serious proposal, it would have been rolled out much earlier in the campaign.”Bohanan said he thinks that some tax cuts can stimulate the economy but that Gansler’s plan probably would cost the state revenue without providing much benefit.

Gansler said his proposal was modeled after one championed by President Obama on the federal level and would “reduce taxes for working families at a time when the costs of living are rising and every dollar counts.He said he would pay for his plan through savings in state procurement reform and other government efficiencies, as well as closing a corporate tax loophole.Qualifying taxpayers would get their credits after filing their income tax returns. Households that qualify for the earned income tax credit would not be eligible.

Gansler spokeswoman Katie Hill said the campaign waited to share the plan until Gansler was certain he could find the funds.

During the tenure of O’Malley (D), the legislature has raised a series of taxes, including personal income taxes on high earners, the corporate income tax, the sales tax, the gas tax, the alcohol tax and the tobacco tax.

Del. Heather R. Mizeur (Montgomery), the third candidate in the Democratic race, is proposing an overhaul of the income tax brackets that she says would provide relief of $50 to $150 a year for an estimated 90 percent of Marylanders. Under her plan, which was issued in November, the tax burden could increase for higher earners.

Brown campaign manager Justin Schall dismissed Gansler’s plan as “just another in a long parade of irresponsible and reckless campaign promises from an increasingly desperate campaign.” Brown has said he will give the tax code a comprehensive look after taking office but has not proposed specific changes to personal income taxes.

“This is about waiting versus leading,” said Mizeur spokesman Steven Hershkowitz. “While Delegate Mizeur has been leading on relief for the middle class and progressive tax reform since last fall, the attorney general waited until two weeks before the primary and the lieutenant governor wants to wait until after the election.”

All Republican gubernatorial candidates have called for cutting income taxes Two of them — Harford County Executive David R. Craig and Charles County businessman Charles Lollar — have called for phasing out the tax.

Gansler previously proposed rolling back the state’s corporate income tax rate from 8.25 percent to 6 percent, to match the level in Virginia.