Hours before South Korea’s National Assembly was expected to vote on impeaching President Yoon Suk Yeol on Saturday, the surrounding area was dense with protesters calling for the impeachment.

Demonstrations in the city and around the country have intensified since Mr. Yoon’s audacious, though short-lived, declaration of martial law on Tuesday plunged South Korea into political crisis. The Saturday rally at the National Assembly was poised to be the largest one yet, and it had a festival-like atmosphere as it kicked off. Many parents brought along their young children.

Big screens and sound systems were set up along the three-quarter mile stretch of road leading up to the National Assembly, broadcasting speakers and performers leading the crowd in chants and songs, many with lyrics calling for Mr. Yoon’s impeachment.

The crowds grew so large that Seoul’s subway operator closed three nearby stations, and people continued to flow in, moving through an area that police had closed off to traffic. People carried signs, as well as blankets to bundle up against the temperatures, which have hovered near freezing all week. Chants and music could be heard from blocks away.

Organizers used Facebook to arrange cross-country transportation: shuttle buses from cities hours away from Seoul and even plane rides from Jeju Island. On X, people shared names that protesters could give at nearby cafes to get free drinks.

While most of the attention was on the crowds outside the National Assembly, in another part of Seoul a much smaller group of Mr. Yoon’s supporters gathered in one of the city’s main plazas. Mr. Yoon’s low approval rating plunged further this week. But thousands of his supporters sang anthems and waved South Korean and U.S. flags on Saturday.

Qasim Nauman contributed reporting from Seoul.

The New York Times