The sweeping criminal justice reform package that has been in the works for about three years on Beacon Hill could land on the governor's desk by the end of the day Wednesday.

Both branches of the Legislature plan to take votes on accepting the conference committee report (S 2371) on Wednesday. The compromise is not subject to amendments, just an up-or-down vote, and passaged is expected.

The House had originally planned its final votes on the criminal justice bill for Thursday but an aide to Speaker Robert DeLeo said Wednesday morning that the House had rearranged its schedule to take up criminal justice sooner.

With the passage of the justice system reform bill at hand, advocates on Wednesday shifted their focus to Gov. Charlie Baker, who has recommended more modest changes and has not yet weighed in on many of the major policy changes included in the compromise legislation.

The Massachusetts Communities Action Network and other groups called on Baker to sign the bill when it reaches his desk.

Bill supporters said their four-year effort has yielded "a comprehensive bill covering circumstances during arrest, prosecution, imprisonment and treatment there, parole, probation, reentry, access to jobs for ex-prisoners, access to drug treatment" and said the bill would have been more narrow if not for their lobbying.

"One turning point in the campaign to pass this bill was when it seemed the Legislature and Governor might only pass the limited proposals that came out of the Council of State Governments report and not a much broader and needed set of reforms," the coalition said in a statement. "We pushed back with demonstrations and engaging legislators. To their credit, the Legislature dug in and passed a comprehensive bill."

The state's district attorneys, a group criminal justice reform advocates have viewed as their opposition, did not raise any significant concerns with the compromise proposal this week but also suggested some changes are necessary.

Norfolk District Attorney Michael Morrissey, president of the Massachusetts District Attorney Association, said the organization has not met since the conference committee report was released but said he and his colleagues respect the "difficulty and complexity" of what the Legislature has done.

"As we have from the beginning, we applaud the Legislature for making some necessary and welcome changes -- of note are the strengthening some drug laws, reduction of fines and fees, limiting collateral consequences and addressing multiple-offense impaired driving. It's clearly the result of hard work and thoughtful compromise," Morrissey said in a statement. "In that same spirit, we will also continue to work productively with the legislature and the Governor where further clarification and technical improvements are needed to move this sweeping bill forward."

The bill would eliminate some mandatory minimum sentences for what lawmakers described as "low-level drug offenses," including first and second offenses for cocaine possession, and require district attorneys to create pre-arraignment diversion programs for veterans and those suffering from mental health and substance abuse disorders.

It would also make eligible for expungement from criminal records some crimes committed by offenders up to age 21, while adults would be able to apply to have their records expunged of crimes that are no longer considered illegal in Massachusetts, such as possession of marijuana.

Sen. William Brownsberger, the Senate chair of the Judiciary Committee and the lead Senate negotiator on the bill, described the current system lawmakers are looking to reform as a "sprawling bureaucracy that ensnares people but from which they cannot escape."

The legislation includes a measure recently pushed by Baker to amend the state's fentanyl trafficking law to allow prosecutors to bring a trafficking charge -- which carries a sentence of up to 20 years -- for offenders caught with a mixture of 10 grams or more that contains any amount of fentanyl.

Baker and law enforcement officials last month noted the current law requires prosecutors to prove that a drug sample has at least 10 grams of pure fentanyl, which the state drug lab is not equipped to detect.

The conference committee report also recommends scheduling fentanyl and carfentanil, two deadly synthetic opioids that have contributed to a rising percentage of opioid overdose deaths, as Class A narcotics, and adopting the federal drug registry for all synthetic opioids so that the state can keep up with the evolving drug market.

The passage of the compromise legislation -- which cannot be amended under legislative rules -- will come after months of private negotiations in the Legislature over what could become a signature achievement for the Legislature this election year.

The Senate is also expected Wednesday to take up a separate piece of legislation that Baker filed last year, and which passed the House on Nov. 14, that grew out of a Council of State Governments (CSG) study of the state's criminal justice system. That bill (H 4012) recommends pathways for some inmates to rehabilitate themselves and get out of prison early.

"I'm looking forward to reviewing the criminal justice bill. I'm hoping that the CSG comes out of that as a companion piece," Baker told reporters Friday. "That was a big item on the legislative agenda at the start of the year."

Thursday's House agenda now includes a midyear spending bill and a bill financing local road and bridge repairs.