Sen. Cory Booker announced late Tuesday that he will no longer accept campaign contributions from political action committees of for-profit companies, following the example of some of his fellow Democrats.

"I heard from constituents today asking about corporate PAC contributions," the New Jersey Democrat said. "I'm joining several of my colleagues & no longer accepting these contributions. Our campaign finance system is broken. I thank @StopBigMoney for their work—it’s time to pass campaign finance reform."

I heard from constituents today asking about corporate PAC contributions. I'm joining several of my colleagues & no longer accepting these contributions. Our campaign finance system is broken. I thank @StopBigMoney for their work—it’s time to pass campaign finance reform. — Cory Booker (@CoryBooker) February 14, 2018



His tweet includes the Twitter handle of End Citizens United, a group that has endorsed a number of candidates who "are standing up against Big Money by rejecting corporate PACs contributions in each of their campaigns." The name of the group is a nod to the 2010 Supreme Court ruling which found the government cannot restrict political contributions from corporations.

Booker accepted $1.8 million from business PACs from 2013-2018, according to Open Secrets, which tracks campaign contributions.

Booker became the fifth U.S. senator to reject corporate PAC money; he was preceded Tuesday by Sen. Kirsten Gillibrand, D-N.Y.

“Because of the corrosive effect of corporate money in politics, I’ve decided from this point on I am no longer accepting corporate PAC checks into my campaign,” Gillibrand said in a video announcing her decision. “We have a system where corporations can spend unlimited money that isn’t even disclosed, so there’s no transparency.”

She was endorsed by End Citizens United.

Sens. Bernie Sanders, I-Vt., Elizabeth Warren, D-Mass., and Maria Cantwell, D-Wash., have also pledged to reject corporate PAC contributions.

Booker, Gillibrand, Sanders, and Warren have been floated as possible 2020 presidential candidates.