BOSTON — A tax-exempt group backed by Republicans is taking aim at Democratic lawmakers with a series of blistering mailers that criticize a controversial vote earlier this year to give themselves a pay raise.

The Massachusetts Fiscal Alliance, founded by GOP businessman and congressional candidate Rick Green, is targeting nearly 40 Democrats up for reelection to the House of Representatives and Senate next year, including Reps. Theodore Speliotis, of Danvers, and Ann-Margaret Ferrante, of Gloucester.

The group has blanketed 29 House districts and nine Senate districts with a barrage of "educational flyers" that blast the raises.

Speliotis, who is seeking reelection from a district that includes Danvers and part of West Peabody, accused it of distorting the issue.

"They've really gone over the top this time," he said. "It's a pure political piece to highlight an unpopular vote. There's nothing educational about it."

One mailer targeting Speliotis asks: “Have you ever received a 40 percent raise or a $20,000 expense allowance?" The glossy flyer lists the lawmaker's Statehouse office number and urges people to call and demand that he "change his position on pay raises for politicians."

Paul Craney, the Fiscal Alliance's executive director, said the group stands behind its claims. He said voters were outraged over the pay raise.

“It’s up to the lawmakers to defend their vote to give themselves a raise,” he said. “We’re just putting that information out there for people.”

The Boston-based group created a database -- http://www.massfiscal.org/lawmaker1617 -- using state payroll records to show how much lawmakers' pay went up because of the raises.

Salary hikes for lawmakers that got them range from 11 percent to 145 percent, factoring in base pay raises, committee assignments and stipends.

In January, the Democratic-controlled House and Senate voted to approve a bill providing nearly $18 million in pay raises for top lawmakers, statewide elected officials and judges.

The vote was even more controversial given that it was the first action of the new two-year legislative session.

Gov. Charlie Baker, a Republican, vetoed the raises. Lawmakers voted went mostly along party lines, with GOP lawmakers opposed, to override his veto.

Not every lawmaker got a pay raise, and several Republicans decided not to take the additional money.

But the new law substantially increased the compensation paid to House and Senate leaders and chairpersons of legislative committees.

House Speaker Robert DeLeo and Democratic Senate President Stan Rosenberg saw their stipends increase from $35,000 to $80,000, bringing each leader’s aggregate pay to $142,547. The law also bumped stipends for leadership and committee assignments between $30,000 and $60,000 a year.

"There was no public debate on these raises and no discussion about where the money would come from," Craney said. "They just pushed it though."

The increase in leadership pay came after all 200 lawmakers saw a base pay increase this year of 4.2 percent, to $62,547 per year, under a 1998 constitutional mandate requiring automatic adjustments based on changes in median household income.

It also gave them the sixth-highest salary of lawmakers in 10 full-time state legislatures in the country.

Legislative leaders defended the raises, arguing that stipends raised in the compensation package had been stagnant for more than 30 years.

Maurice Cunningham, a political science professor at the University of Massachusetts at Boston, said Mass Fiscal's attacks on Democrats are "sleazy" and "wildly misleading,” but they also could hurt lawmakers in next year's elections.

"People don't like the idea of lawmakers voting themselves a pay raise,” he said. "So it could be an issue for Democrats."

For several years, MassFiscal has hammered away at Democrats for supporting increased spending and taxes, raising the gas tax by indexing it to inflation and “denying veterans priority housing benefits over illegal immigrants.”

The group maintains a “scorecard” that rates how certain lawmakers vote on budgetary items.

Not surprisingly, Republicans get the best rankings, with Senate Minority Leader Bruce Tarr at the top of the list. Most Democrats -- including those representing the North of Boston region -- get a "zero" percent ranking.

MassFiscal is registered as a nonprofit, operating under a classification that allows it to raise and spend money on voter education but prohibits it from advocating for any particular candidate. Under federal law, the group doesn't have to disclose the sources of its funding.

Democrats have for years accused the group of flouting state campaign finance laws by operating like a political committee. Democrats complain the group refuses to disclose donors whose money it uses to pay for negative mailers and robocalls.

Rep. Jerald Parisella, D-Beverly, was targeted several years ago by the group.

"They were trying to claim that I had voted to deny housing to veterans, which is absurd. I’m a veteran,“ said Parisella, an Army reservist who served in Iraq.

In the past, Democrats have challenged Mass Fiscal’s non-profit status and called on state officials to intervene, but their efforts have fallen short.

Last year, the Office of Campaign and Political Finance ordered the group to disclose the source of a $500 contribution used in a special election.

An spokesman for the campaign finance office declined to say whether any complaints had been filed over the latest round of mailers.

Craney called the criticism by Democrats a “distraction” that “targets the messenger.”

"We're just putting the information out there," he said. "That's our mission statement -- holding lawmakers accountable -- and we're not going to stop."

Christian M. Wade covers the Massachusetts Statehouse for North of Boston Media Group’s newspapers and websites. Email him at cwade@cnhi.com.