Nearly half of Massachusetts voters oppose a measure to expand charter schools in the state, a new poll from WBUR and MassINC Polling has found.

Forty-eight percent of poll respondents say they will vote against the November ballot question, while 41 percent are planning to support the measure. Eleven percent are undecided.

Additionally, 46 percent of likely voters say charter schools would drain money from other public schools, while 38 percent say they would not.

The charter school referendum — Question 2 — proposes to allow up to 12 new charter schools a year statewide. The question has the support of Governor Charlie Baker, and business leaders are among those providing financial support.

The survey was conducted between Sept. 7 and 10 and focused on the four ballot questions facing Massachusetts voters in November.

The poll also found that 50 percent of respondents support the move to legalize marijuana in Massachusetts, while 45 percent oppose it. Five percent are undecided or said they don’t know.

Among voters 60 and older, pollsters found that 56 percent oppose legalizing marijuana and 39 percent support it. Among voters younger than 30, 65 percent support legalization.

On the two other questions, the poll found:

■ A clear majority — 62 percent — of likely voters back a question that would mandate all eggs sold in Massachusetts be from hens that are cage-free.

■ A majority, 52 percent, oppose approving a slot parlor near the Suffolk Downs racetrack.

The poll surveyed 506 likely voters over land lines and cellphones. It has a margin of error of 4.4 percentage points, according to WBUR. Steve Koczela, president of The MassINC Polling Group, has worked for supporters of expanding charter schools.

Nicole Hernandez of the Globe staff contributed to this report. John R. Ellement can be reached at ellement@globe.com. Follow him on Twitter @JREbosglobe.