WASHINGTON — A Republican policing bill hit a roadblock Wednesday as Senate Democrats blocked it while saying it was inadequate, leaving the parties to decide whether to negotiate a compromise or walk away despite public outcry over the killings of Black Americans.

The impasse threatens to turn the nationwide protests over the deaths of George Floyd, Breonna Taylor and others into another moment that galvanizes the nation but leaves lawmakers unable to act. Common ground is not out of reach.

But the legislation is stalled, for now, with Democrats refusing to agree to open debate as they push for greater changes in police tactics and accountability. Three senators — independent Sen. Angus King of Maine and two Democrats — voted with Republicans to advance the bill, but they fell short of the 60-vote threshold needed to proceed.

“If you don’t think we’re right, make it better, don’t walk away,” implored Sen. Tim Scott of South Carolina, the only Black Republican senator and the author of the GOP bill.

Yet the outlook is deeply uncertain with Congress unable to swiftly respond even as the public demands policing changes. Much as lawmakers have failed to act during times of crisis on gun control or immigration changes, there’s a familiar standoff despite broad support.

The GOP’s Justice Act is seen by Republicans and Democrats as a starting point in the broader debate over how best to change policing practices as demonstrations in cities large and small focus on law enforcement and racial injustice. It would create a national database of police use-of-force incidents, restrict police chokeholds and set up new training procedures and commissions to study race and law enforcement.

The package is not as sweeping as a Democratic proposal, which mandates many of the changes but would also hold police liable to damages in lawsuits. There are similarities on some issues, lawmakers say, but also vast differences. Civil rights leaders urged a no vote on the GOP bill, while police and business groups have urged the parties to find common ground.

King, who caucuses with Democrats, said in a statement the Senate version “does not enact nearly enough change,” but he said that voting it down risked ending Senate discussion on the subject “for the foreseeable future.” Sen. Susan Collins, R-Maine, hit Democrats in a statement, saying their move was “truly stunning.”

Ahead of Wednesday’s vote, Trump tweeted his support for the GOP bill. He said it would be “great for both people of color and police.” Trump tweeted, “Hope to sign it into law ASAP!”

During a GOP lunch Tuesday, Scott played for colleagues the racist voicemail messages he has recently received, according to a Republican granted anonymity to discuss the private meeting. Senators were shocked. Some suggested Scott needs security protection because some of the calls were threatening, said a Scott aide.

As talks potentially continue, Democrats are trying to force Republicans to the negotiating table. The House is set to approve the Democrats’ bill later this week. The two would ultimately need to be the same to become law. Neither bill goes as far as some activists want with calls to defund the police and shift resources to other community services.

House Speaker Nancy Pelosi, D-California, has indicated she is eager to enter talks with the Senate, a signal the door is not closed to compromise. But in a CBS News Radio interview Tuesday, Pelosi said Republicans need to step up with a better bill and were “trying to get away with murder, actually — the murder of George Floyd.”

The comment drew sharp rebuke and calls from Republicans for her to apologize. Political risks of inaction are high, as the public wants to see policing changes after nearly a month of constant demonstrations nationwide, in cities large and small, forcing a worldwide reckoning over law enforcement and racial injustice.

Associated Press writers Lisa Mascaro, Laurie Kellman and Andrew Taylor and BDN writer Michael Shepherd contributed to this report.