The push by Senate leaders to limit qualified immunity for police from lawsuits has been thrust to the center of the debate over policing as senators return to Beacon Hill on Monday hoping to advance reform legislation to a vote after days of delays.

The bill in the Senate proposes to make Massachusetts the second state in the country to limit the principle of qualified immunity, following in the footsteps of Colorado. While the federal delegation doesn't always get involved in state-level debates, U.S. Rep. Ayanna Pressley said the Senate bill would make a "powerful statement" to the rest of the country.

Pressley has filed legislation in Congress with Rep. Justin Amash of Michigan to end qualified immunity at the federal level. The Boston Democrat said police should be held to the same professional standards as doctors and lawyers, who can both be sued for malpractice and negligence.

"It has come to my attention that many detractors are attempting to weaken the bill," Pressley said in a statement. "Let me be clear, qualified immunity is a barrier to accountability and healing and we must dismantle it."

The Senate bill would end qualified immunity for police except in cases where no reasonable defendant would have reason to believe that there conduct was in violation of the law. Sen. William Brownsberger, the former co-chair of the Judiciary Committee, has defended the language, and Senate President Karen Spilka and Sen. Julian Cyr, among others, have taken to social media to defend the provision of the policing bill.

The limits on qualified immunity are opposed by the state's largest union of police officers, who say cops should not have to worry about the threat of lawsuits as they carry out their jobs on the streets of Massachusetts cities and towns.

The Senate returns to session Monday morning after days of attempting to debate the police reform bill, only to be stymied by Republican Sen. Ryan Fattman. Fattman has used procedural motions to delay the debate in what he said is an effort on behalf of both Democrats and Republicans to both get more time to review the complex bill and rework some of its measures.

Some advocates for police reform plan to rally for the Senate bill at the State House Monday morning, according to Rev. Willie Bodrick, II, associate pastor of the Historic Twelfth Baptist Church.

Our Revolution Massachusetts was also urging its supporters to contact senators whose support for limiting qualified immunity, they said, was "soft." Those senators included Sen. Nick Collins of South Boston, Sen. Diana DiZoglio of Methuen, Sen. Paul Feeney of Foxborough, Sen. John Keenan of Quincy, Sen. Ed Kennedy of Lowell, Sen. Mark Montigny of New Bedford, Sen. Su Moran of Falmouth and Sen. Marc Pacheco of Taunton.