Whispers among members of the Democratic National Committee suggest there is growing anxiety about the rise of Vermont Sen. Bernie Sanders.

Roughly half a dozen DNC members have quietly discussed reversing historic reforms that reduced the outsize influence of unpledged delegates, known as superdelegates, before the party picks its nominees for president and vice president this summer, according to Politico.

The presidential primary of 2016 left Democrats bitterly divided, as liberal supporters of Sanders asserted superdelegates gave Hillary Clinton an unfair advantage. In August 2018, the DNC passed a measure to block superdelegates, which comprise elected officials and party leaders, from casting a vote for any presidential candidate unless a second ballot is required at the 2020 national convention, stripping them of power.

Former Vice President Joe Biden, 77, has the edge over the field in national polls this election cycle, but Sanders, 78, generally leads by a small margin in the polls in Iowa, which will hold its first-in-the-nation caucuses on Monday, and in New Hampshire, which will hold its primary on Feb. 11.

His surge, coupled with the popularity of fellow liberal Sen. Elizabeth Warren, 70, has given rise to the possibility that Sanders enters the July convention with the most pledged delegates but not enough to win the nomination. Another scenario has Biden with the majority but Sanders and Warren with enough delegates combined to outnumber his. The prospect of an ugly, contested convention has some DNC members spooked.

A text message exchange between William Owen, a DNC member from Tennessee, and another member offers a glimpse into the conversations about changing the rules.

“I do believe we should re-open the rules. I hear it from others as well,” said the message sent by the unidentified DNC member to Owen, who opposes changing the rules. He said this fellow member added: “It would be hard, though. We could force a meeting or on the floor."

A statement by DNC Chairman Tom Perez rejected the idea of doing away with the superdelegate reform.

"Absolutely not. We put in the work to ensure power was returned to the grassroots. We will be following the rules set forth by the DNC. We will not bend on this; we will not change our rules," he tweeted in response to the Politico report on Friday.

Still, there is visible frustration among members of the Sanders team. They have voiced outrage in recent days in response to decisions by the DNC perceived as maneuvers that could elbow out the left-wing candidate if his campaign gains traction.

Nina Turner, the national co-chairwoman of the Sanders campaign, said Perez's list of picks for committees charged with overseeing the convention and helping to create the party's platform was a "slap in the face." The Sanders camp also lashed out on Friday after the DNC changed a rule, which removed the requirement for candidates to meet a minimum number of donors starting with the Feb. 19 debate in Nevada. The rule gives Michael Bloomberg, a billionaire who is self-funding his bid and not accepting campaign contributions, a pathway to the debate stage.

With the group of DNC dissenters said to be relatively small at this point, other Democrats openly cast doubt that a rules change is possible, particularly for this election cycle.

Don Fowler, a former DNC chairman from South Carolina who opposed the 2018 reforms, said he has participated in the "casual" conversations but would not identify the members involved. “But I want to be clear that I would not be a party to any effort to do that in the 2020 convention … It’s bad sportsmanship," he said.

"I don’t believe it’s wise to reopen a wound once it has healed," said former DNC Chairwoman Donna Brazile, who is a member of the Rules and Bylaws Committee.