Sen. Cory Booker, D-N.J., vowed in a Tuesday tweet to stop accepting campaign donations from political action committees with ties to for-profit corporations.

Booker, long rumored to be considering a presidential run in 2020, joins five other high-profile senators and potential presidential hopefuls such as Sen. Elizabeth Warren, D-Mass., and Sen. Kirsten Gillibrand, D-N.Y. Sen. Bernie Sanders, the independent Vermont senator who caucuses with Democrats, has also said he would stop taking donations from corporate PACs.

"I heard from constituents today asking about corporate PAC contributions," Booker wrote on Twitter. "I'm joining several of my colleagues & no longer accepting these contributions."

Democratic senators from solidly blue states are seizing the opportunity to take the moral high ground when it comes to campaign contributions and call for campaign finance reform. But vulnerable Democrats fighting to keep their Senate seats in states President Donald Trump won in 2016, such as Florida, Indiana, Missouri, Montana and Wisconsin, could fall under pressure to join their colleagues.

Being forced to snub corporate campaign donations in such challenging states would be a blow to key Senate Democrats, many of whom would find it difficult to outspend deep-pocketed conservative donors like the Kochs.

In Florida, for one, sitting Democratic Sen. Bill Nelson could be faced with a challenge from Republican Gov. Rick Scott, who is expected to spend heavily on his campaign if he chooses to run.

In Wisconsin, Sen. Tammy Baldwin is already seeing more money being spent against her than any other Democratic Senate candidate in the country.

Until his announcement, Booker, who is up for re-election in 2020, had accepted about $1.8 million from corporate PACs between 2013 and 2018, according to the Center for Responsive Politics. Gillibrand, who is running for re-election this year but is in a safe seat, had received contributions from PACs linked to such companies as Time Warner and Johnson & Johnson.

Gillibrand's announcement was endorsed by End Citizens United, a grassroots PAC aimed at amending a 2010 decision by the U.S. Supreme Court that certain independent campaign expenditures by corporations, non-profits and others cannot be restricted.

An End Citizens United spokesperson confirmed to CNBC that the organization knew of only one Republican who has made a similar pledge: Francis Rooney, the incumbent U.S. Representative for Florida's 19th District.

Montana Rep. Greg Gianforte pledged not to take corporate PAC money in his 2017 campaign, but has since reversed his stance, according to a Feb. 7 report by Roll Call.

Booker's move came soon after Gillibrand released a video on Twitter announcing that she would not accept campaign contributions from corporate PACs.

"Because of the corrosive effect of corporate money in politics, I have decided from this point on I am no longer accepting corporate PAC checks into my campaign," Gillibrand said.

"I will no longer accept donations from corporate PACs, and I wanted to share why I've made that decision," she tweeted. "I hope you'll join me in doing everything we can to fight to reform our broken campaign finance system."