U.S. Rep. Ayanna Pressley is pushing back against a new Democratic Congressional Campaign Committee (DCCC) rule that penalizes pollsters, strategists and other campaign vendors if they work for Democratic candidates challenging incumbents in primaries.

The Boston Democrat, who unseated longtime Rep. Michael Capuano in Massachusetts' 7th district in November, said the rule “slams the door” on future campaigns just like hers, making it harder for young candidates and activists to advance in the party — particularly women and people of color.

“I think it can certainly contribute to what are already cultural and institutionalized barriers to get us to closer to achieving leadership parity, both in gender and in race,” Pressley tells WBUR. That negative impact will be felt “on both sides of this, both on the candidate side and on the vendor side,” she says.

Pressley says even before the rule, some vendors were told “not to come anywhere near” her campaign lest they face retaliation from Democratic Party leaders.

She says she was grateful for the “brave” staffers who joined her campaign anyway, and says the success of primary challenges like hers and New York Rep. Alexandria Ocasio-Cortez’s should serve as a valuable model for other Democratic candidates to follow rather than a problem that needs to be stifled.

DCCC spokesman Cole Leiter said the rule fulfills a campaign vow by Illinois U.S. Rep. Cheri Bustos, the DCCC chair, to protect the House’s Democratic majority.

“When Chairwoman Bustos was running to lead the DCCC, she stood up in front of her colleagues and made a promise to stand with and protect every Member of the most diverse caucus in Congressional history as we work to defend and grow our Democratic majority,” Leiter said in a statement. “This transparent policy follows through on that exact promise and will protect all Members of the Democratic Caucus — regardless of where they fall within our big tent.”

Pressley says she was proud that her campaign drew a large number of first-time primary voters and produced a surge of support from Latinx voters and college students. She says she wants other candidates to duplicate that success in other districts, particularly those made up of underserved communities.

“We accomplished something unique and special,” Pressley says. “But that is not anything that I want to be an anomaly. This is what I want to be more of the norm.”

Politico reported that several progressive House members clashed with Bustos of Illinois over the rule during a closed-door meeting Wednesday.

Members of the Congressional Progressive Caucus said the proposed rule would create a “monopoly” of campaign vendors with DCCC approval, and "blackball" others who work for other Democrats, the report said.