On March 15, hundreds of thousands of demonstrators across Brazil flooded the streets. It was the biggest mobilization since June 2013, when millions took to the streets in protest that began over increased public transit fares and grew to encompass a range of other causes, including World Cup megaprojects, the poor state of public education, the need for political reform and many others.

A different cause united this month’s mobilizations. Protesters could be heard chanting Cold War–era anti-communist slogans, demanding the impeachment of President Dilma Rousseff and even calling for army intervention in domestic politics. Thirty years after the end of Brazil’s military dictatorship, Rousseff and her center-left Workers’ Party (PT) face a growing challenge from the right.

The PT has held national power in Brazil for the last 13 years. But Rousseff is increasingly politically isolated. Re-elected last fall by a slim margin, she now has to contend with the most conservative National Congress since 1964 as well as a decelerating economy, hostile media and a corruption scandal that implicates her party. She has very low approval ratings and has increasingly alienated her party’s traditional base of trade unionists and social movement activists, many of whom are disappointed with her pro-market political appointments. Although opposition parties are not yet calling for Rousseff’s impeachment, there is no question that difficult times lie ahead.

Corruption is a very serious issue. But the recent protests have been conspicuously silent about political reforms — such as full public campaign financing — that could help address the problem. And although politicians from several major parties, including the opposition, are currently under investigation for corruption, the only political party mentioned during the protests was the PT. In fact, the one overriding theme of the protests was the anti-PT sentiment.

What accounts for this hostility? Last weekend’s protests must be understood as part of a growing conservative backlash in Brazil against years of PT-directed redistribution. Elite and middle-class hostility toward minorities, the poor and their political patrons has now come to the fore in unprecedented ways.

Eyewitnesses agree that the protesters were generally whiter and wealthier than the typical Brazilian. A survey of participants from Porto Alegre and São Paulo confirms this: Nearly 70 percent were college-educated (in a country where 11 percent are), and more than 40 percent were in the highest income bracket (occupied by only 3 percent of the general population). Former Finance Minister Luiz Carlos Bresser-Pereira remarked that he was witnessing, for the first time in his life, “collective hatred on the part of elites, of the rich, against a party and a president. It wasn’t worry. It was hatred.”