A Democratic senator hit out Monday at leftist activists who followed her into a bathroom to make their case for a massive White House spending package she has been blocking -- highlighting the divisions threatening President Joe Biden's economic agenda.

Kyrsten Sinema, one of two conservative-leaning Democratic holdouts in the Senate on Biden's $3.5 trillion social welfare package, was assailed at Arizona State University, where she lectures.

The senator said in a statement her students, who were also using the bathroom when the protesters struck, had been "unfairly and unlawfully victimized."

"It is unacceptable for activist organizations to instruct their members to jeopardize themselves by engaging in unlawful activities such as gaining entry to closed university buildings, disrupting learning environments, and filming students in a restroom," she said.

Video posted to Twitter on Sunday by progressive group Living United for Change in Arizona (LUCHA) showed youth activists waiting outside Sinema's classroom and demanding to speak to her as she emerged.

"Actually, I am heading out," she replied as she walked to a bathroom.

Footage taken by a protester in the bathroom shows an activist haranguing the senator outside the stall that she is using. 

https://twitter.com/LUCHA_AZ/status/1444729925408153601

"I don't think they're appropriate tactics, but it happens to everybody," Biden told reporters at the White House when asked about the incident and another protest outside a fellow senator's houseboat.

"The only people it doesn't happen to are people who have Secret Service standing around them. So it's part of the process."

LUCHA defended its tactics at the Phoenix campus, saying it "wouldn't have to resort to confronting (Sinema)... if she took meetings with the communities that elected her."

Sinema, 45, and fellow centrist Senator Joe Manchin have angered the Democratic rank and file by opposing the high price proposed for the social spending bill at the heart of Biden's domestic agenda.

The package is a grab-bag of policies aimed at making the economy fairer by improving benefits for children, college students and seniors while expanding health care coverage and battling climate change.

Sinema has not telegraphed her goals in negotiations, leaving confusion over what it would take to get her on board. Manchin, 74, is pushing for a pared-down version pegged at $1.5 trillion. 

In a more orderly protest than in Arizona, activists gathered in a flotilla of kayaks by Manchin's houseboat on the Potomac river in Washington over several days last week to protest against his opposition to the package.