With Pulitzers for both explanatory and investigative reporting under his belt, New York Times Reporter Eric Lipton knows more than a little about the kind of journalism ProPublicans crave.

This week, he talks with Senior Reporter Jesse Eisinger and Assistant Managing Editor Eric Umansky about his Pulitzer win this year, for an investigation on influence peddling among congressional leaders and state attorneys general.

Highlights of their discussion:

• The ways his piece took reporting on lobbying to the next level by focusing not just on who was donating, but also on the outcomes of the contributions. While causality is generally hard to establish, Umansky says, "this seemed much more clearly quid pro quo." (2:33)
• How Lipton organized reams of source material -- including 6,000 pages of emails resulting from open-records requests in 25 states -- to begin building his article. "It was almost as if the open-records responses were writing the story," says Lipton, who moved to a library in at The Times’s office and stacked piles of paper to make sense of it all. (7:31)
• The “ecosystem of influence,” where the role of the traditional, registered lobbyist is “becoming less and less important and interesting," Lipton says. "It’s the broad campaign that corporations are creating, and all the surrogates that are being paid, often without disclosure – that’s the play that I think is most interesting in the lobbying world." (13:47)

Hear their conversation on iTunes, SoundCloud and Stitcher, and read Lipton’s Pulitzer-winning series "Courting Favor." Subscribe to ProPublica’s podcasts to hear conversations like these each week.