BOSTON - Lawmakers’ decision to award themselves pay raises earlier this year was an unpopular move with around three quarters of the electorate, according to a poll sponsored by a conservative group that argues the pay hike could imperil progressives’ push for a tax hike next year.

The pay raise law, approved over Gov. Charlie Baker’s veto, increased the compensation of the speaker and the Senate president from about $97,000 to $142,000 while other lawmakers’ pay increased by lesser but still substantial amounts depending on their leadership positions or committee chairmanships.

Massachusetts Fiscal Alliance, a group that has rankled Democrats since its founding five years ago, calculated that the average pay raise was 40 percent. Except for top leadership positions, lawmakers holding only one stipend-eligible position saw their pay rise by less than 40 percent, and backbenchers received only an increase in their expense accounts.

Thirty percent of voters said they would be “much less likely” to support someone at the polls who voted for his or her own 40 percent pay raise, and another 43.6 percent said they would be “less likely,” according to the survey conducted by Virginia-based Advantage, Inc.

The poll that was publicized Wednesday found 8.8 percent of voters would be more likely to support a politician who voted for their own 40 percent raise. The increase in lawmakers’ expense accounts, another provision of the pay raise law, was even less popular, according to the poll.

Jim Eltringham, vice president at Advantage, Inc., said the poll of 500 registered voters conducted in mid-June was modeled to resemble the electorate in 2018. The margin of error was 4.4 percent.

According to the survey, two thirds of voters were very or somewhat aware of the pay raise vote, which was lawmakers’ first major agenda item this year.

No Republicans supported the pay raise bill and nine House Democrats and three Senate Democrats opposed the measure, which passed overwhelmingly in both branches.

Paul Craney, spokesman for Mass Fiscal, said the poll also showed that Democrats who voted for the pay raise bill created some challenges for the Democrat-led push to add a 4 percent surtax onto incomes over $1 million. Mass Fiscal opposes that tax.

In back-to-back sessions about 70 percent of the House and Senate voted to advance the ballot question to amend the constitution with a surtax that proponents say could generate $2 billion for transportation and education. Unless it is blocked by the courts, the question will appear on the 2018 ballot.