The Senate's Judicial Proceedings Committee is whittling away at their version of the legislation, which was introduced as the Trust Act.
In its current form, the bill would explicitly bar police from questioning people about immigration or citizenship status. It also would bar jail officials from holding people past their release date for immigration purposes, unless federal officials present a warrant signed by a judge. And it directs the state attorney general to create guidelines to limit immigration enforcement at schools, hospitals and courthouses.
The bill would allow local jails to continue programs that partner with Immigration and Customs Enforcement to identify possible immigration violators in custody.
Gov. Larry Hogan has promised to veto the bill if it is passed by the legislature.
Miller said Maryland would not become a "sanctuary state."
"Our churches are not sanctuaries, our colleges are not sanctuaries, our cities are not sanctuaries," said Miller, a Calvert County Democrat.
"The bill as it passed the House is not going to pass the Senate," he said.
Miller added that he does want to protect immigrants from intrusive inquiries.
"We need to protect all citizens, no matter how they got here, from being hindered while going about their lives," he said.
Miller said he has not been lobbying members of the Senate Judicial Proceedings Committee, who are reviewing the bill.
The committee spent nearly an hour wrestling with the the legislation Tuesday night, going section by section and discussing which parts to keep and which to remove. They held off on taking a final vote.
Sen. Bobby Zirkin, the committee's chairman, said it was most important to him to make clear that police can't stop people for the purpose of inquiring about immigration.
Zirkin, a Baltimore County Democrat, said he doesn't want police to arrest individuals as a pretext to ask them about immigration.
Though Zirkin said the practice is already prohibited by a Supreme Court ruling, "there's a statement to be made to reinforce that in state law."
Some on the committee are not convinced the bill is a good idea. Sen. Michael Hough, a Frederick County Republican, said the bill "completely ties the hands of law enforcement."
If the Senate passes a different version of the bill than the House, the two chambers would have to reconcile the differences before the end of the General Assembly session on April 10.