WASHINGTON — What began as a murmur in Republican cloakrooms has escalated into one of the most public intraparty ruptures of the election cycle, as Marjorie Taylor Greene launched an unusually direct attack on former President Donald Trump, House Speaker Mike Johnson, and what she described as a Republican leadership culture “built on intimidation and silence.”

Ms. Greene’s denunciations, delivered through a cascade of social media posts and follow-up comments to conservative outlets, marked a striking departure for a lawmaker long associated with the party’s most combative wing. She accused senior Republicans of sidelining dissent, concealing internal disagreements, and enforcing loyalty through pressure rather than persuasion. In one widely shared image, chains appear to snap apart, accompanied by a caption describing the act of “breaking free from a bully.”

People familiar with the matter said the rupture traces back to a private confrontation earlier this month involving Ms. Greene and senior party figures. According to two individuals briefed on the exchange, voices were raised and warnings delivered, leaving aides stunned by the intensity of the dispute. Those people spoke on the condition of anonymity to describe internal party discussions.

The fallout was swift. Republican allies who once amplified Ms. Greene’s message sought distance, while critics seized on the episode as evidence of a party struggling to reconcile its populist base with institutional leadership. Within hours, screenshots of posts and clips from interviews ricocheted across political media, fueling speculation about deeper divisions ahead of a consequential election year.

Neither Mr. Trump nor Speaker Johnson directly addressed Ms. Greene’s allegations on the record. A spokesman for Mr. Johnson declined to comment, citing the speaker’s focus on legislative priorities. Mr. Trump, who has maintained a delicate balance between encouraging loyalty and managing rival factions, posted unrelated messages emphasizing unity and electoral strategy.

For many Republicans, the episode underscores a broader tension: a movement forged through grievance politics now confronting its own internal hierarchies. Ms. Greene framed her break as a moral stand, arguing that party leaders had drifted from transparency and accountability. “This isn’t about personalities,” she said in an interview. “It’s about whether we tell the truth to our voters.”

Democrats, meanwhile, portrayed the clash as symptomatic of Republican dysfunction. “When a party defines itself by loyalty tests, eventually the tests turn inward,” said one senior Democratic aide.

Political analysts cautioned against overstating the immediate impact. Ms. Greene retains a devoted following, but her influence depends on coalition-building within a closely divided House. “This is less a single eruption than a stress fracture,” said one Republican strategist. “It reveals pressure that’s been building for months.”

Still, the timing is delicate. With legislative deadlines looming and campaign messaging sharpening, party leaders face renewed questions about discipline and direction. Several Republicans privately expressed concern that public infighting could distract from policy goals and complicate fundraising.

Ms. Greene suggested the episode was only the beginning, hinting that additional details could emerge. Whether those claims materialize or fade amid the churn of political news, the spectacle has already accomplished something rarer in Washington: it has exposed, in real time, a party grappling with the costs of its own rhetoric.

As the dust settles, Republicans must decide whether this confrontation becomes a cautionary tale—or a catalyst for further fragmentation. Either way, the episode has laid bare a reality often hidden behind closed doors: unity, in this moment, is neither assumed nor assured.