Peter Overby for NPR:

As Sens. Elizabeth Warren, Kamala Harris and Kirsten Gillibrand jumped into the Democratic presidential nomination contest, they staked out the same position against corporate campaign cash.

“The money in politics is corrupting. It controls everything,” Gillibrand told a gathering in Des Moines, Iowa, last month. “You’ve got to take on the whole system, and you have to get money out of politics. And that’s why, as a very small first step, I’m not taking corporate PAC money.”

Small as it is, this pledge to reject corporate PAC money has become a cornerstone of the Democrats’ primary contest. It helped Harris to raise $1.5 million online from small donors in the 24 hours after she announced. Warren’s campaign didn’t release a total for the post-announcement surge, but she said she got contributions from all 50 states, the District of Columbia and Puerto Rico.