A dry policy debate over bipartisan policing legislation exploded on Tuesday afternoon into a heated and personal clash among three Democratic senators, offering a rare glimpse of the internal fight in their party over how to take on President Trump.

The spectacle started in the least dramatic way possible: Senator Catherine Cortez Masto, Democrat of Nevada and a former attorney general and federal prosecutor, asked for unanimous consent to pass a package of policing bills, including one to reauthorize support for mental health services for law enforcement officers, and another to make recruits eligible for funding for training programs.

It quickly went off the rails when Senator Cory Booker, the progressive New Jersey Democrat, rose to object, accusing Ms. Cortez Masto of being “complicit” with an authoritarian president.

Things got personal and nasty after Senator Amy Klobuchar of Minnesota, a longtime rival to Mr. Booker who also ran for the 2020 Democratic presidential nomination and a cosponsor of some of the measures, noted that he failed to attend a key committee meeting where members debated the legislation and voted unanimously to move it to the Senate floor.

“Don’t question my integrity,” Mr. Booker shouted so loudly his voice could be heard outside the Senate chamber. “Don’t question my motives. I’m standing for Jersey, I’m standing for my police officers, I’m standing for the Constitution and I’m standing for what’s right. And dear God, if you want to come at me that way, you’re going to have to take it up with me. There’s too much on the line right now in America.”

Because the Justice Department was “weaponizing” public safety grants against states and cities that “resist the Trump policy agenda,” Mr. Booker said, Democrats should oppose the bills unless they added language to safeguard any law enforcement grants from politicization.