 -- Elizabeth Warren isn't too keen about former President Barack Obama's $400,000 fee to address a Wall Street conference on healthcare this fall.

"I was troubled by that," the Massachusetts senator said Thursday during an interview with the SiriusXM show "Alter Family Politics" on Radio Andy.

She then proceeded to discuss her disdain for "the influence of money" in the nation's capital.

"One of the things I talk about in the book ["This Fight is Our Fight"] is the influence of money," she said. "I describe it as a snake that slithers through Washington. And that it shows up in so many different ways here in Washington. People understand the money that goes into campaign contributions. And when I say 'understand.' I don't mean they think it's okay, but at least people see it. The money that goes into hiring lobbyists, but it's also the money that goes into bought-and-paid-for experts, the money that goes into think tanks that have these shadowy funders."

ABC News confirmed Obama's six-figure speaking fee for the Wall Street conference with his office. It was first reported by Fox Business.

"As we announced months ago, President Obama will deliver speeches from time to time," Obama spokesman Eric Schultz told ABC News. "Some of those speeches will be paid, some will be unpaid, and regardless of venue or sponsor, President Obama will be true to his values, his vision, and his record."

And specifically addressing the Wall Street conference, Schultz continued, "He recently accepted an invitation to speak at a health care conference in September, because, as a President who successfully passed health insurance reform, it's an issue of great importance to him. With regard to this or any speech involving Wall Street sponsors, I'd just point out that in 2008, Barack Obama raised more money from Wall Street than any candidate in history -– and still went on to successfully pass and implement the toughest reforms on Wall Street since FDR."

But Obama's post-Oval Office life isn't all about six-figure speaking engagements, says Schultz. "And while he'll continue to give speeches from time to time, he'll spend most of his time writing his book and, as he said in Chicago this week, focusing his post-presidency work on training and elevating a new generation of political leaders in America," the former president's spokesman said.