One of Hillary Clinton’s top attack dogs — former U.S. Rep. Barney Frank — has surfaced as a new flashpoint in the battle between Bernie Sanders and establishment Democrats, winning a powerful DNC post at this summer’s nominating convention.

Frank has long been a thorn in Sanders’ side but was just named co-chairman of the DNC Rules Committee, a position that could give Frank considerable say over the Milwaukee convention.

The appointment has escalated tensions between the DNC and the Sanders campaign, which are already beginning to divide the party.

The abrasive Frank, a Newton Democratic congressman until retiring in 2013, was one of Clinton’s leading surrogates in the 2016 race and in the past has blasted Sanders’ “holier-than-thou” attitude and penchant for calling both political parties corrupt.

“Bernie Sanders has been in Congress for 25 years with little to show for it in terms of his accomplishments,” Frank said in a Slate interview four years ago.

Frank has also attacked voters who are drawn to Sanders.

“I am disappointed by the voters who say, ‘OK, I”m just going to show you how angry I am,’” Frank said.

Yet now Frank is in prime position for shaping the convention that could nominate Sanders as the nominee, and Sanders supporters fear a repeat of 2016, when Democratic officials sought to make sure Sanders wasn’t the nominee.

Thanks, DNC.

Frank’s emergence is actually good for the media who like to blow up big battles within the party, but bad for any hopes for a smooth convention.

Sanders forces are already outraged by Frank’s appointment to the Rules Committee, as well as other appointments for former Clinton supporters to committees that will influence the convention.

They include Hillary Clinton’s former campaign chairman, John Podesta, who in leaked DNC emails trashed Sanders and said he should be “ground to a pulp.”

Also landing a seat on one of the DNC convention committees is Bakari Sellers, a former surrogate for Clinton in 2016.

“I don’t have a problem with Bernie getting in the race, ‘when is he getting out’ is probably a better question,” Sellers tweeted in February of last year.

A number of other Democratic officials and operatives with Massachusetts ties also landed appointments to the DNC committees on Rules, Platform and Credentials.

They include Attorney General Maura Healey, vice-chairwoman of the Credentials Committee, state Democratic chair Gus Bickford, a member of the Credentials Committee, and James Roosevelt, Jr., co-chairman of the Credentials Committee.

DNC Chairman Tom Perez has sought to make the 2020 convention and nominating process more fair, weakening the power of superdelegates and creating transparent rules for which candidates qualify for the debates.

But he’s going against the ornery Sanders forces — “Bernie bros” — who believe going in that the deck is stacked against them.