In the lead-up to the midterm elections, a wave of populist Democrats has emerged across the United States, reflecting widespread frustration with the political establishment, including within their own party. Candidates such as Melat Kiros, Sam Forstag, and Brian Poindexter exemplify this trend, running insurgent campaigns grounded in anti-establishment sentiment and a desire to address systemic economic and political grievances.

Ms. Kiros, a 29-year-old Ethiopian American lawyer and self-described democratic socialist, recently unseated long-serving Representative Diana DeGette in a Denver primary by a 13-point margin. She attributes her victory in part to the mobilization of younger voters—particularly those from Generation Z—who have grown up amid economic uncertainty and pandemic-related challenges. Ms. Kiros has positioned herself as a challenger to entrenched party norms, critiquing politicians who accept corporate donations while pledging progressive reforms such as Medicare for All.

In Montana, 32-year-old Sam Forstag, a wilderness firefighter and smokejumper, stepped into the political arena after budget cuts led to layoffs within the U.S. Forest Service, affecting many of his colleagues. While not aligning with democratic socialism, Mr. Forstag shares a deep dissatisfaction with political leadership. He criticized the Democratic Party for repeatedly backing President Joseph R. Biden Jr., asserting that the party’s choice of an aged incumbent failed to inspire confidence among voters concerned about the stakes of the upcoming elections.

Similarly, Brian Poindexter, a 47-year-old union ironworker from Ohio, is campaigning in a Republican-leaning district against incumbent Max Miller, a Trump ally currently facing allegations of domestic abuse—claims Mr. Miller denies. Mr. Poindexter draws upon his working-class background to express discontent with both major parties, emphasizing the growing inequalities in wealth and power that he believes political elites ignore.

Experts suggest that this surge in populist candidacies has been propelled partly by the emergence of a politically active younger generation grappling with issues such as affordability and public health crises. Elaine Kamarkc, director at the Center for Effective Public Management, notes that while media coverage often depicts these intra-party divisions as revolutionary, the current political landscape within the Democratic Party is more evolutionary than seismic.

On the Republican side, some candidates are also attempting to channel voter anger. Aaron Flint, an Army veteran and radio host campaigning in Montana, speaks to working-class frustrations but faces obstacles due to his party’s alignment with former President Donald Trump. While Mr. Trump’s rhetoric once challenged political elites and “endless wars,” his continued influence complicates Republican efforts to present a fresh populist message.

The contrast between these insurgent Democrats and the establishment reflects a broader political tension as candidates seek to navigate voter dissatisfaction while appealing to diverse constituencies. For many of these populist candidates, the priority is to break from traditional political structures, offering alternatives they argue are more attuned to the economic struggles and political disillusionment felt by many Americans today.