"This is a profound moment, it is a moral moment," said Senator Cory Booker, D, a co-author of the Democrats' proposal. "The call is for us to act."
Yet Congress, as it has so many times before when confronted with crisis — on gun control or immigration changes supported by broad segments of the population — is expected to stall out, for now.
Lawmakers are hesitant to make moves upsetting to voters as they campaign for the November election.
And US President Donald Trump, facing his own re-election, is an uneven partner with shifting positions on the types of changes he would accept from Capitol Hill.
Ahead of a test vote tomorrow, Senate Majority Leader Mitch McConnell acknowledged it may fall short. If so, he vowed to try again, hoping to pass legislation before a July 4 holiday recess.
The Republican bill's author, Senator Tim Scott of South Carolina, warned against a partisan, political debate that chisels away confidence in the nation's institutions.
"This is not about them or us," said Scott, the only Black Republican in the Senate. It's about young people and others, he said, "who are afraid to jog down the street or get in their car and drive."
The GOP's Justice Act 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.
It is not as sweeping as a Democratic proposal, which mandates many of the changes and would hold police liable to damages in lawsuits. There are similarities on some issues, lawmakers say, but also vast differences.
Senate Democratic leader Chuck Schumer and top Democrats signalled they would oppose the Republican bill as "not salvageable," as they demand negotiations on a new, bipartisan package with more extensive changes to law enforcement tactics and accountability aligned with their own Democratic bill.
The Democrats are being backed by the nation's leading civil rights organisations and the lawyer, Benjamin Crump, representing the families of Floyd and Taylor, two African Americans whose deaths in police interactions sparked worldwide protests over racial bias in policing.
"The Black community is tired of the lip service," Crump said in a statement.
As talks potentially continue, Democrats are trying to force Republicans to the negotiating table to strengthen Democrats' hand.
The House is set to approve the Democrats bill later this week.
The two bills, the House and Senate versions, would ultimately need to be the same to become law.
House Speaker Nancy Pelosi has indicated she is eager to enter talks with the Senate over the two approaches, which is a signal that Democrats are not closing the door to a compromise.
Neither bill goes as far as some activists want with calls to defund the police and shift resources to other community services.
"We're ready to make a law, not just make a point," McConnell said as he opened the Senate today.
He said Americans "deserve better than a partisan stalemate."
Republicans insisted Democrats would have a chance to amend the Senate bill if they allow the debate to begin. But Democrats countered there is no agreement their changes would be up for consideration.
"Now is the time for Congress to pass legislation that will bring real change," said Senator Kamala Harris, D, a co-author with Booker and House leaders on the Democratic bill.
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.
- AP