The Senate appeared on the cusp of failure Tuesday as Republicans and Democrats struggled to find consensus on how to address a national crisis over race and policing and answer the public demand to overhaul law enforcement tactics.

Democrats criticized a Senate Republican plan as inadequate, arguing that it falls far short of a substantive transformation of controversial policing practices, and they laid the groundwork to stall the measure. Republicans countered that their proposal was a viable starting point for legislation and said Democratic resistance was a sign that the party was interested only in scoring political points months ahead of the elections.

The gridlock on Capitol Hill stood in contrast to the growing public support for policing reforms in the four weeks since the death of George Floyd, an unarmed black man who died in police custody, galvanized the nation with demands for racial justice. Three states have already enacted new policing laws that restrict controversial practices such as chokeholds and aim to make law enforcement more accountable. Dozens more are moving aggressively to change police practices.

Sen. Cory Booker (D-N.J.) on June 23 criticized Senate Republicans for failing to address the “cycle of death and tragedy” via their policing bill. (The Washington Post)

But in a politically divided Washington, Republicans and Democrats were moving on separate tracks, with no apparent attempt at a compromise that could ultimately pass Congress and make its way to President Trump.

“We can’t answer the people’s demand for accountability with watered-down politics,” said Sen. Kamala D. Harris (D-Calif.), a former presidential candidate who is on the shortlist to be the party’s choice for vice president. “I will say we cannot answer their demand with this Republican attempt to obstruct real progress and real justice in our country.”

Harris, along with Senate Minority Leader Charles E. Schumer (D-N.Y.) and Sen. Cory Booker (D-N.J.), sent a letter to Senate Majority Leader Mitch McConnell (R-Ky.), arguing for bipartisan negotiations on the policing overhaul bill before the legislation faces a key test vote Wednesday.

In the letter, Booker and Harris — the Senate’s two black Democrats — and Schumer called the GOP bill “not salvageable.”

Republicans have urged Democrats to let the bill proceed to the Senate floor, where negotiations and amendment votes could be used to revise it.

Sen. Tim Scott (S.C.), the Senate’s sole black Republican and the chief author of the GOP bill, who has spoken repeatedly about the racial discrimination he personally has faced from law enforcement, said that if Democrats “won’t even start it, that tells me this is already over.”

“This is about Louisville, Ky. This is about North Charleston. This is about Minneapolis. Our legislation covers those points,” said Scott, listing the sites of recent officer-involved deaths of black Americans. “If our friends on the other side want to figure out a path forward for those places and those citizens, let’s get there.”

The partisan standoff raised questions about whether Congress — which in recent years has struggled to enact ambitious legislation beyond averting crises and keeping the government running — is capable of responding to the incidents of police brutality, the nationwide protests and the demands for change less than five months before November’s elections.

A national Associated Press-NORC survey conducted this month found a sweeping desire nationwide for police reform, with clear majorities across racial and party lines supporting changes such as requiring officers to wear body cameras and prosecuting those who use excessive force.

But at least on Tuesday, efforts to overhaul policing practices on the federal level seemed destined for failure.

The Senate GOP plan incorporates a number of Democratic proposals, such as legislation to make lynching a federal hate crime that has been championed by Scott, Harris and Booker, as well as a national policing commission that is the brainchild of Sen. Gary Peters (Mich.), a Democrat up for reelection this fall in a state Trump won in 2016.

But there has been no attempt to negotiate the differences between the Democratic and Republican visions for policing bills, with the two parties disagreeing about the extent of a federal mandate to alter practices at the thousands of local police departments nationwide.

That difference in fundamental philosophies is apparent on one major issue: whether to explicitly ban no-knock warrants, issued by a judge who allows officers to enter a residence without being announced.

Under the Democratic legislation, set to pass the House this week, such warrants would be banned in federal drug cases, and federal funding would be conditioned on local police agencies barring the practice. The Senate GOP bill calls on states and localities to report to the Justice Department when such warrants are used, and it would punish those that do not do so by withholding federal funding.

The Republican bill also leaves intact the “qualified immunity” standard that Democrats want to erode, making it easier for law enforcement officials to be sued for misconduct.

Democratic senators noted that dozens of civil rights and racial justice groups have come out in opposition to the Republican-drafted bill, and they insisted on bipartisan talks to get the legislation more to their liking at the outset. Among the more influential opponents of the GOP plan are the NAACP Legal Defense and Educational Fund and Benjamin Crump, an attorney for the Floyd family.

“Who do you trust on police reform in America?” Booker asked at a Tuesday afternoon news conference. “The NAACP or Mitch McConnell?”

The campaign of former vice president Joe Biden, the presumed Democratic presidential nominee, said that he “fully supports Senate Democrats doing exactly what voters sent them to Washington to do by demanding bipartisan negotiations to move the ball forward on police reform legislation.”

“The American people are crying out for their leaders to finally make meaningful progress on the systemic injustice that has plagued our country for generations,” Biden campaign spokesman TJ Ducklo said in a statement. “Now, Senate Republicans need to step up and show they are listening.”

The stalemate on Capitol Hill stands in contrast to action across the country, where more than 250 bills have been introduced in 26 states on the issue of police reform since Floyd’s May 25 death, according to a database compiled by the nonpartisan National Conference of State Legislatures.

On June 12, after a single day of debate in the legislature, Iowa Gov. Kim Reynolds (R) signed into law legislation restricting the use of chokeholds and preventing police officers who have been fired for misconduct from being hired elsewhere in the state.

“To the thousands of Iowans who have taken to the streets calling for reforms to address inequalities faced by people of color in our state, I want you to know this is not the end of our work. It is just the beginning,” Reynolds said at the signing ceremony, as chants of “Black lives matter!” broke out.

The same day, New York Gov. Andrew M. Cuomo (D) signed a series of police-related measures, including one that criminalized chokeholds and repealed an obscure 1976 law that shielded police disciplinary and personnel records from public scrutiny.

Last week, Colorado passed its own sweeping police bill into law, banning chokeholds, issuing new mandates on the use of body cameras and, in what observers say is a first, making officers financially liable if they are found guilty of violating a person’s civil rights.

At the signing ceremony Friday, state Sen. Rhonda Fields, a Democrat and one of the legislation’s sponsors, acknowledged the tens of thousands of protesters who have marched in the streets across the state in recent weeks.

“We heard your cry, and the people of Colorado did not look away,” Fields declared.

One state where progress has notably stalled is Minnesota, where politicians had vowed sweeping changes to policing in the aftermath of Floyd’s death. But the efforts are suddenly in doubt after Republicans abruptly adjourned a special session of the legislature when they could not reach a compromise with Democrats.

Gov. Tim Walz and other Democrats, who control the state House, had pushed for far-reaching police overhauls, including a statewide ban on “warrior training,” new rules on the use of deadly force and accountability measures that would make it easier to fire problem officers.

Republicans, who control the state Senate, supported a shorter list of 11 changes, including banning chokeholds and requiring officers to stop colleagues from using excessive force. Hours before adjourning, they also proposed reforming the arbitration process — which many departments say makes it difficult to fire problem officers — by shifting those cases to outside administrative law judges, but it wasn’t enough to reach a deal.

In Washington, the House plans to vote this week on the Democratic-crafted bill that would mandate several changes, including the ban on chokeholds, prohibitions on some no-knock warrants, and establishment of a national database to track police misconduct and make it easier to hold officers accountable in civil and criminal court for misconduct.

McConnell said if the Senate bill does not advance Wednesday, he will take procedural steps to tee it up again in the future. Republicans later noted that Democrats can exert significant influence on the progress of the bill, because it would require 60 votes not just to start work on the legislation but also, separately, to move it to a final passage vote.

“I hope none of you are falling for this nonsense that somehow our Democratic colleagues would be disadvantaged by getting on the bill,” McConnell told reporters Tuesday afternoon. “Once you get on the bill, if you conclude you’ve been treated unfairly, you don’t have to get off the bill.”

There were barely any signs Tuesday that Republicans would accede to demands from Democrats to negotiate at least a bipartisan template for the bill before Wednesday’s vote.

Scott, Booker, Harris and Sen. Richard J. Durbin (Ill.), the No. 2 Senate Democrat, met privately earlier Tuesday in an apparently futile attempt to negotiate, and Scott said later that there was no “discernible” progress toward a deal that would allow his legislation to advance.

Meanwhile, Sen. John Cornyn (R-Tex.), one of McConnell’s closest allies, said he was “not really all that interested in negotiating with hostage-takers,” referring to Democrats.

“I just think it’s mindless, it’s mindless obstruction,” Cornyn said. “I just can’t. This is the worst I’ve seen it.”

Matt Viser contributed to this report.