Sen. Elizabeth Warren, D-Mass., and South Bend (Indiana) Mayor Pete Buttigieg, two of the leading candidates for the Democratic presidential nomination called into question each other's committment to transparency.

Warren asked Buttigieg to disclose the names of his campaign bundlers Thursday and to open his fundraisers to the press.

“The mayor should be releasing who’s on his finance committee, who are the bundlers who are raising big money for him, who he’s given a title to and made promises to,” Warren said. “And he should open up the doors so that the press can follow the promises that he’s making in these big-dollar fundraisers.”

Buttigieg released the names of 23 campaign bundlers in April, but his campaign has not disclosed any names since.

Warren also called on Buttigieg to disclose the names of the clients he had during his three years working for the consulting firm McKinsey -- a request echoed by the New York Times editorial board

“I think that voters want to know about possible conflicts of interest,” Warren said. This request in particular is complicated by the fact that Buttigieg has signed a nondisclosure agreement with the firm that forbids him from mentioning his clients. The South Bend mayor has called on the firm itself to release the names of his clients, arguing it has the power to do so.

Buttigieg's campaign countered Warren by issuing a challenge of its own. Buttigieg senior adviser Lis Smith called on Warren to release tax returns, laying out her income from private sector legal work done in the 1990s:

Warren has released 11 years worth of tax returns, covering her time in public office but covering her life in the private sector.