For years, Senator Lindsey Graham appeared to occupy one of the safest seats in American politics. Representing South Carolina, a state that has reliably voted Republican in presidential and Senate races, Mr. Graham weathered controversies that might have ended the careers of less entrenched lawmakers. This week, however, newly circulated polling and a surge of online backlash have forced a reassessment — both inside Washington and back home.

The numbers, shared privately among political operatives before leaking into public discussion, suggest a level of voter dissatisfaction that few in Mr. Graham’s orbit anticipated. While he is not trailing a declared challenger outright, aides familiar with the data say the erosion of support is significant enough to raise alarms. In a state where incumbents typically enjoy wide margins, even a modest drop can be politically destabilizing.

The reaction was swift. Clips of Mr. Graham’s past statements — particularly moments where his public positions shifted sharply over time — began resurfacing across social media. Commentators framed the footage as evidence of inconsistency, while supporters argued it reflected pragmatism in a volatile political era. Either way, the renewed scrutiny amplified a sense that the senator’s long-standing political formula may be under strain.

At the center of the debate is Mr. Graham’s relationship with Donald Trump. Once a vocal critic, he later became one of the former president’s most visible allies in the Senate. That loyalty helped insulate him from primary challenges in the Trump era, but it may now be producing diminishing returns. Some voters, particularly independents and college-educated Republicans, have expressed fatigue with what they see as reflexive partisanship.

“People don’t necessarily hate him,” said a South Carolina-based Republican strategist who has reviewed recent surveys. “They’re just tired. And tired voters are unpredictable.”

Insiders say the frustration did not emerge overnight. Concerns about economic pressures, foreign policy priorities, and congressional gridlock have been building for months. Mr. Graham’s high-profile role on national television and in Washington hearings has kept him visible, but visibility cuts both ways. Each appearance reinforces his prominence — and his association with decisions that some voters increasingly question.

Donors are also watching closely. While there is no sign of a funding collapse, several major contributors are said to be reassessing their commitments, particularly if a credible challenger emerges. In South Carolina politics, donor hesitation can quickly translate into momentum for opponents, even in races that once seemed foregone conclusions.

Democrats, while encouraged by the turbulence, remain cautious. South Carolina’s electorate still leans heavily Republican, and flipping the seat would require an unusually favorable environment. More immediately, analysts suggest the greater threat to Mr. Graham could come from within his own party — either through a primary challenge or a fractured base that turns out unevenly.

Mr. Graham has sought to project confidence. In recent remarks, he dismissed unfavorable polling as “noise” and emphasized his record on national security and judicial appointments. Allies argue that his experience and seniority remain valuable assets, particularly in a polarized Senate where influence is tied to longevity.

Still, even some supporters privately acknowledge that the mood has shifted. “He’s always been able to ride things out,” said one longtime Republican donor. “The question is whether this is another storm — or whether the climate has changed.”

Political history is filled with moments when early warning signs were ignored. Polling dips, viral criticism and donor unease do not guarantee defeat, but they often signal vulnerability. For a senator who has spent decades navigating Washington’s power structures, the challenge now may be less about policy and more about perception.

As strategists recalibrate and potential challengers watch closely, one reality is clear: Lindsey Graham’s political standing, once assumed unshakable, is now being actively tested. Whether this episode marks a temporary stumble or the beginning of a deeper reckoning will depend on how voters — not pundits or algorithms — ultimately respond.