SOUTH BEND, INDIANA - APRIL 14: South Bend Mayor Pete Buttigieg announces that he will be seeking the Democratic nomination for president during a rally in the old Studebaker car factory on April 14, 2019 in South Bend, Indiana.

Democratic presidential contender Pete Buttigieg, the mayor of South Bend, Indiana, will return thousands of dollars donated to his campaign by registered federal lobbyists and will not accept such contributions any longer, his campaign said Friday.

Buttigieg faced mounting pressure from his party's progressive base to disavow lobbyist money. He was the last major Democrat running for president to swear off it.

"Mayor Pete will not be influenced by special-interest money, and we understand that making this promise is an important part of that commitment," campaign manager Mike Schmuhl wrote in an email to supporters.

The campaign said it will return $30,250 from 39 individuals that it had received so far. It will also bar registered lobbyists from serving as bundlers — a type of major fundraiser.