Known to her supporters simply as Heidi, she is a vibrant 36-year-old who speaks rapidly and passionately. Adorned with a tattoo of the Polish-German activist Rosa Luxemburg on her left arm, she has captivated an impressive audience, amassing nearly a million followers on TikTok and Instagram. Until recently, her presence in German politics was rather understated, but as of last Sunday, she has emerged as a significant political figure.

Heidi Reichinnek played a pivotal role in the unexpected outcome of Germany’s parliamentary elections: a remarkable revival of Die Linke, meaning “The Left.”

Only a month ago, Die Linke appeared poised to fall short of the 5 percent threshold necessary for parties to secure representation in Germany’s Parliament, known as the Bundestag. However, on election day, the party gained nearly 9 percent of the votes, translating to 64 seats in the Bundestag. They became one of just five parties to obtain multiple seats in the new legislative body, alongside the Christian Democrats, Social Democrats, the far-right Alternative for Germany (AfD), and the Green Party.

This impressive comeback can be attributed to young voters, rising living costs, dissatisfaction with conservative politicians, and a dynamic social media campaign that combined elements of celebration with a spirit of defiance.

In a climate where many German politicians are shifting rightward on topics such as immigration, and amid a significant increase in support for the Alternative for Germany (AfD), Ms. Reichinnek, co-leader of Die Linke in the Bundestag, has effectively harnessed the frustrations of liberal, young voters.

They positioned themselves as a formidable counterbalance to a more conservative government, which is likely to be led by Friedrich Merz, a businessman at the helm of the Christian Democrats, who has adopted a tougher stance on border security and immigration.