A brewing weeklong fight inside the Democratic National Committee burst into the open on Thursday as the party’s chairman, Ken Martin, rebuked one of his vice chairs and moved to stop him from intervening in Democratic primary races while serving as a top party official.
The vice chair, David Hogg, 25, had announced last week that he planned to spend money in Democratic primaries through his outside group, Leaders We Deserve, and that he hoped to raise $20 million for the effort.
That set off a storm of criticism from Democrats angry at the idea that a top party official would be putting his finger on the scale in primary contests. On Thursday, Mr. Martin responded publicly for the first time, declaring, “No D.N.C. officer should ever attempt to influence the outcome of a primary.”
Mr. Martin said he had “great respect” for Mr. Hogg and understood his goals, yet he issued what amounted to an ultimatum: Mr. Hogg was “more than free” to fund primary challenges, just not as an officer of the D.N.C.
Mr. Martin made his comments on a call with reporters announcing plans to expand grants to the party’s operations in red states.
At a private meeting last month, all of the committee’s officers — except Mr. Hogg — signed a pledge promising to remain neutral in primary races.
Mr. Hogg has done a blitz in the news media, appearing on cable shows to make his case after The New York Times first reported his plans, which he stipulated would be limited to races for safe Democratic seats. Mr. Hogg said his goal was to elect a younger generation of Democrats and replace older incumbents he saw as less effective. Still, as he faced blowback on Capitol Hill, his group donated $100,000 to the Democratic Congressional Campaign Committee.
Jane Kleeb, the chair of the Nebraska Democratic Party and the president of the Association of State Democratic Committees, said Mr. Martin would introduce a series of previously planned party changes that would include putting neutrality in the bylaws — meaning Mr. Hogg could not serve in his position if he were still pursuing his plan.
The package will go before the party’s membership in August, she said.
Ms. Kleeb said the importance of party neutrality was made clear during the divisive 2016 primary race between Hillary Clinton and Senator Bernie Sanders of Vermont, when party leaders supported Mrs. Clinton.
“David got elected to be a D.N.C. officer,” Ms. Kleeb said of Mr. Hogg’s vice-chair post. “He did not get elected to primary Democrats.”
Ms. Kleeb said she had spoken with Mr. Hogg privately and told him that he could remain a part of D.N.C. leadership if he walled himself off from his outside group’s endorsement decisions, as some union leaders have done.
”He can’t have both,” she said. “He has to make a decision.”
Mr. Hogg did not immediately respond to a request for comment.