Freshman Rep. Alexandria Ocasio-Cortez is resisting a new incumbent-favoring policy of House Democrats’ campaign arm by urging her supporters to donate directly to individual candidates instead of to the party.

The New York Democrat, who won her own seat last year after upsetting a veteran Democratic incumbent, called it “divisive” and “harmful” for the Democratic Congressional Campaign Committee to adopt a new policy prohibiting its vendors from working with political newcomers who challenge sitting Democrats.

“The @DCCC’s new rule to blacklist+boycott anyone who does business w/ primary challenges is extremely divisive & harmful to the party,” Ocasio-Cortez tweeted on Saturday. “My recommendation, if you’re a small-dollar donor: pause your donations to DCCC & give directly to swing candidates instead.”

Ocasio-Cortez specifically urged her Twitter followers to donate to several other freshman representatives, including Mike Levin (D-Calif.), Lauren Underwood (D-Ill.) and Katie Porter (D-Calif.).

Another freshman, Rep. Ayanna Pressley (D-Mass.), tweeted: “it’s very possible that I wouldn’t be in Congress” had the DCCC’s new restrictions been in effect last year.

The DCCC notified political vendors of its new policy earlier this month, sending them a list of hiring standards that say the party “will not conduct business with, nor recommend to any of its targeted campaigns, any consultant that works with an opponent of a sitting Member of the House Democratic Caucus.”

The change affects an array of firms that provide campaign services such as strategy, advertising and polling to Democrats running for House seats, and could make it extremely difficult for outsiders to persuade top consultants to sign on.

A DCCC spokesman defended the new policy, saying DCCC Chairman Cheri Bustos (D-Ill.) wants to protect the most diverse Democratic House caucus in congressional history.

“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,” spokesman Cole Leiter said in a statement.

But the move drew sharp rebukes from some within the caucus, who viewed it as a move to deter primary challengers. Reps. Pramila Jayapal (D-Wash.), Mark Pocan (D-Wis.) and Ro Khanna (D-Calif.) met this week with Bustos to express strong opposition to the policy, which, Khanna said, “stifles competition and blackballs any consultant who works for a challenger.”

“This unprecedented grab of power is a slap in the face of Democratic voters across the nation,” Khanna told reporters. “Voters are sick of the status quo holding on to power and stifling new voices. They are sick of D.C. politicians who care more about holding on to power than a true competition of ideas.”

Khanna said they stressed to Bustos that her predecessor, Rep. Ben Ray Luján (D-N.M.), had never advanced such a restriction, nor had House Speaker Nancy Pelosi (D-Calif.).

“It’s something even Rahm Emanuel would not have done,” Khanna said, referring to the Chicago mayor and former Illinois lawmaker who served as DCCC chairman from 2005 to 2007.

“Let’s be clear,” he added. “If this policy remains in place it will mean that we will not allow new Ayanna Pressleys or AOCs to emerge. It’s simply wrong.”

Sean McElwee, a Democratic activist and pollster who has encouraged a wave of primary challenges to moderate Democrats, wrote in an email newsletter that the DCCC had become the “White Male Centrist Campaign Protection Committee” of the House.

“It’s truly wild that House Democrats saw a wave of progressive outsiders bring new energy to the party and thought, ‘No, stop that,’ ” McElwee wrote. “But they did, so we have to fight back.”

Ironically, while the DCCC’s move is said to have discouraged some challengers from making 2020 runs, it is also complicating the plans of Democrats who want to unseat some of the freshman class’s most left-wing members.

Some activists in Rep. Ilhan Omar’s (D-Minn.) district, angered by her tweets criticizing Israel and the influence of AIPAC, have cast around to find a primary challenger. And in Detroit, some African American leaders want to consolidate around a single challenger to Rep. Rashida Tlaib (D-Mich.), who won just 31.2 percent of the vote in a primary where the black vote was divided between four candidates.

Both of those recruitment efforts, and campaigns, could be stymied by the DCCC’s rules.

Rachael Bade and Dave Weigel contributed to this report.