Trump, who met with law enforcement officials at the White House, characterised Democrats as having "gone CRAZY!"
As activists beyond Capitol Hill call to restructure police departments and even to "defund the police", the president tweeted, "LAW & ORDER, NOT DEFUND AND ABOLISH THE POLICE." He declared later, "We won't be dismantling our police."
Democratic leaders pushed back, saying their proposal would not eliminate police departments — a decision for cities and states — but establish new standards and oversight.
Joe Biden, the presumed Democratic presidential nominee, "does not believe that police should be defunded", said spokesman Andrew Bates.
The Justice in Policing Act, the most ambitious law enforcement reform from Congress in years, confronts several aspects of policing that have come under strong criticism, especially as more and more police violence is captured on cellphone video and shared widely across the nation and the world.
The package would limit legal protections for police, create a national database of excessive-force incidents and ban police choke holds, among other changes.
It would revise the federal criminal police misconduct statute to make it easier to prosecute officers who are involved in "reckless" misconduct and it would change "qualified immunity" protections to more broadly enable damage claims against police in lawsuits.
The legislation would ban racial profiling, boost requirements for police body cameras and limit the transfer of military equipment to local jurisdictions.
Overall, the bill seeks to provide greater transparency of police behavior in several ways. For one, it would grant subpoena power to the Justice Department to conduct "pattern and practice" investigations of potential misconduct and help states conduct independent investigations.
And it would create a "National Police Misconduct Registry", a database to try to prevent officers from transferring from one department to another with past misconduct undetected, the draft says.
A long-sought federal anti-lynching bill that has stalled in Congress is included in the package.
House Judiciary Committee Chairman Jerrold Nadler, a co-author with Representative Karen Bass, and Democratic senators will convene a hearing on the legislation on Wednesday.
"The world is witnessing the birth of a new movement in this country," said Bass, chairwoman of the Congressional Black Caucus, which is leading the effort.
While Democrats are expected to swiftly approve the legislation this month, it does not go as far as some activists want. The outlook for passage in the Republican-held Senate is slim.
Senate Majority Leader Mitch McConnell, whose Louisville hometown faces unrest after the police shooting of Breonna Taylor in her home, said he would take a look at potential Senate legislation.
It is unclear if law enforcement and the powerful police unions will back any of the proposed changes or if congressional Republicans will peel off some of their own proposals.
Republicans are likely to stick with Trump, and GOP campaign officials bashed efforts underway in some cities to reallocate police funds to other community services.
Yet McConnell was central to passage of a 2018 criminal justice sentencing overhaul the president signed into law, and some key GOP senators have expressed interest in more streamlined changes to policing practices and accountability.
Senator Mitt Romney, who marched with protesters Sunday, told reporters on Monday at the Capitol that he is working with other Republican senators "to see if we can't fashion a piece of legislation which could receive bipartisan support to make some changes to the way we do our policing".
The chairman of the Judiciary Committee, Senator Lindsey Graham, a Republican, has said his panel intends to hold a hearing to review use of force and other issues, and other GOP lawmakers have suggested Floyd's death could spark more modest changes.
Republican Will Hurd, who marched in support of Floyd in Houston, penned an op-ed on Monday about how his own black father instructed him to respond if he was pulled over by the police, and suggested proposals for changes in police practices.
What started with the Black Lives Matter movement after the death of Michael Brown in Ferguson, Missouri, has transformed with the killings of other black Americans into a diverse and mainstream effort calling for changing the way America polices its population, advocates say.
"I can't breathe" has become a rallying cry for protesters. Floyd pleaded with police that he couldn't breathe, echoing the phrase Eric Garner said while in police custody in 2014 before his death in New York.
"All we've ever wanted is to be treated equally — not better, not worse," said Democrat Representative Hakeem Jeffries.
Biden's own platform reflects much of the approach from congressional Democrats, and his former presidential primary rivals, Cory Booker and Kamala Harris, are co-authors of the package in the Senate.
