Virginia Sen. Tim Kaine is urging the Democratic National Committee to end its tradition of using superdelegates, which activists say diminish the influence of regular voters at the expense of party bigwigs in the presidential nominating process.

"I have long believed there should be no superdelegates. These positions are given undue influence in the popular nominating contest and make the process less democratic,” Kaine wrote in a letter Wednesday to DNC chairman Tom Perez, according to a copy obtained by POLITICO.

The plea from Kaine — himself a former DNC chairman, Hillary Clinton’s 2016 running mate, and a superdelegate — puts him on the side of many backers of Vermont Sen. Bernie Sanders, Clinton’s primary opponent in last year’s race for the White House. Under the current system, elected officials and influential party members get to cast a vote for their preferred presidential candidate with extra weight, regardless of how their state or district votes during the primary.

Pointing to the ongoing work of the Unity Reform Commission appointed last year to review and change the DNC’s nominating process, Kaine urged the group to recommend doing away with the superdelegate system altogether, and by extension encouraged Perez to adopt that proposal.