Pittsburgh (CNN) Pete Buttigieg's presidential campaign on Friday released a list of its bundlers following weeks of trading barbs with Massachusetts Sen. Elizabeth Warren over campaign transparency.

The South Bend, Indiana, mayor has recently faced pressure to name his big-money backers and open his fundraisers to reporters, as other candidates have done. Buttigieg's progressive rivals, including Warren and Sen. Bernie Sanders of Vermont, have emphasized smaller individual donations to suggest that they would be less beholden to moneyed interests.

Former bundlers for Hillary Clinton and Barack Obama's campaigns, as well as a former Obama administration defense official, were among those listed in Friday night's release. In a statement, the campaign claimed it was being transparent.

"As it has in the past, the campaign is making public the names of people who have raised at least $25,000 for the campaign, a threshold lower than both of the previous two Democratic nominees for president," the campaign said.

The statement continued, "In addition to releasing these names, which no other current campaign has done, Pete has also opened his fundraisers to the press. He has made public 12 years of tax returns, he has held three multi-day bus tours with reporters that were completely on the record, and he has committed to restoring daily press briefings in the White House."

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