BOSTON (AP) — A proposed "millionaire tax" constitutional amendment is facing a final legislative hurdle on its way to the 2018 ballot.

On Wednesday, House and Senate lawmakers are scheduled to consider whether the proposal should go before Massachusetts voters next year.

Under the plan, individuals with annual incomes above $1 million would be subject to a 4 percent surtax. The surtax would only apply to portions of income over $1 million. The current income tax rate is 5.1 percent.

Supporters say it would raise an extra $1.9 billion for education and transportation. Critics argue it would hurt the state's business climate and drive away jobs.

The measure must receive the backing of at least 25 percent of lawmakers meeting in Wednesday's joint session. Last year, lawmakers voted 135-57 to advance the measure.