Thousands of supporters of President Yoon Suk Yeol have been camped out for days on the pavement near his home in central Seoul, vowing to block anyone from trying to detain or arrest him.

In a constant rally near the president’s home, supporters have called his parliamentary impeachment “null and void.” On Thursday evening, they waved national flags and light batons and chanted: “Let’s protect Yoon Suk Yeol!”

More came out Friday morning as officials arrived at the residence to execute a court warrant to detain Mr. Yoon for questioning on insurrection charges.

“I came here to save the president and the country!” Kim Suni, 80, said outside his residence in Seoul on Friday.

Mr. Yoon’s abrupt declaration of martial law on Dec. 3 triggered national outrage, prompting the opposition-dominant National Assembly to impeach him and a number of mass demonstrations against him. But Mr. Yoon still had die-hard supporters among mostly older South Koreans, with conservative churches organizing them in large rallies in downtown Seoul.

Many of them have moved near Mr. Yoon’s residence since a Seoul court issued a warrant on New Year’s Eve for officials to detain him for questioning. In a message delivered to his supporters on New Year’s Day, Mr. Yoon called them “citizens who love freedom and democracy” and thanked them for braving the cold weather to show their support.

“I will fight with you to the end to save this country,” Mr. Yoon said.

Cha Myong-in, a former conservative lawmaker, urged Yoon supporters to form “a human chain” to deny officials access to the presidential residence. Dozens of supporters lay on the pavement, with their arms locked, across the alley leading to Mr. Yoon’s residence. Police removed them, with some protesters dragged away.

“The president is like the king, and how can you treat your king like this?” said Lee Young-jin, 65, referring to the court warrant that empowered officials to detain Mr. Yoon. “The presidential guard should throw grenades if necessary to stop them from coming near the president.”

Lee Won-ok, 59, who showed up at the pro-Yoon rally with his white Maltese dog, blamed opposition lawmakers for driving Mr. Yoon to declare his martial law out of desperation.

“They did everything they could to obstruct his work, like slashing his government budget plans,” she said. “This is so unfair because I don’t think President Yoon has done anything wrong.”