Many of them sweltered in the humidity in Singapore last Saturday to listen to him speak at a protest he organised. The message was loud and clear: there's no more room for foreigners here.
Activist Gilbert Goh may not be a household name in Singapore - yet. But he's quickly becoming the Singaporean face of growing xenophobia or patriotic fervour - depending on which camp you're from.
"He dares to speak the truth," said one middle-aged woman who had decided to spend the May Day public holiday attending the peaceful protest with her husband. "Most of us won't dare to say these things in public."
In recent years, Goh has become more vocal in his criticism of immigration policies that he blames for allowing foreigners to steal jobs from Singaporeans.
A career counsellor, Goh runs the website transitioning.org , which aims to help Singaporeans who have lost their jobs. His supporters say he is a true blue Singaporean patriot. But critics recall him using words that can't be printed in any decent newspaper and many struggle to say anything nice at all about the 53-year-old.
"This is ridiculous," Goh told the Sunday Morning Post. "Why does a person who shows so much love for his country deserve to be labelled as a traitor, racist and xenophobe? Singapore is our only home that we know and we have every right to protect it from mismanagement."
Goh's family migrated to Australia five years ago. He is divorced and has a daughter who is an undergraduate in Sydney. His childhood was tough, he says. His father was a taxi driver and his mother worked at a restaurant.
Most people first noticed him in 2011 when he ran in the general election under the National Solidarity Party ticket and lost.
At times, he appears to be pushing the legal limits in the tightly controlled city-state. Police warned him not to deface posters of Prime Minister Lee Hsien Loong at last week's rally and earlier this year, he was warned against plans to burn an effigy of the transport minister.
"I guess I try to stay within the boundaries, but if there comes a day I am arrested for standing up for my country, so be it. All these protests are done for the love of Singapore and Singaporeans."
But critics question Goh's tirades against foreigners.
"A close examination of Goh's past writings before he became so prominent will reveal undercurrents of xenophobia that have always existed," said Siew Kum Hong, formerly an appointed lawmaker in parliament.
In a Facebook post last year, Goh suggested the influx of foreigners was making it tougher for local men to marry local women. He criticised Singaporean women who dated foreign men.
He wrote: "Our women folk also find that ang mohs (a slang term for Caucasians that once had derogatory connotations) are better at making conversation, maybe due to their mastery of the English language and they are also more gentlemanly … More importantly, they provide a direct passport out of Singapore for our women folk when the time comes for them to relocate back to the guy's country - if they ever get hitched."
These days Goh and his supporters are on a crusade against Filipinos in Singapore who are planning independence day celebrations outside a popular mall on Orchard Road next month.
Orchard Road is Singapore's premier shopping and tourist destination. Goh and his supporters say holding the celebration there would violate Singaporeans' sovereign rights.
Prime Minister Lee recently waded into the debate, saying those who harassed the celebration organisers were a "disgrace to Singapore".
Singaporean Bertha Henson, a former news editor who lectures at a university, said the protest was silly.
While Goh's protests helped to shed light on some of the problems faced by Singaporeans, Henson said the government deserved credit for accommodating Singaporeans who felt overwhelmed by foreigners.
The ruling People's Action Party has recently restricted the inflow of foreign talent.
"I have yet to hear Goh acknowledge this properly," said Henson, a popular blogger. "It's always easy to say, too little, too late. But we must acknowledge the immigration policy of welcoming foreigners in large numbers was about a decade in the making. And to roll this back would take time."
Activists also have to realise the impact of fewer foreigners in the workforce, she says.
Some small and medium enterprises say they are unable to find affordable labour in industries which Singaporeans shun. The government is trying to increase the productivity of these companies and help them rely less on foreign labour.
Lee said on Wednesday that the government could not relax its recent restrictions on foreign workers.
"We have to manage the inflow, we have to manage what we can accommodate in Singapore," he told The Straits Times.
Meanwhile a small but growing number of angry locals use the internet to air xenophobic sentiments. From uploading unverified videos of badly behaving foreigners to carrying out witch hunts against those who disparage the wealthy Southeast Asian country, the online lynch mob has been busy in recent years.
Yet Singapore is still regarded as one of the best places for expatriate workers, with the anti-foreigner sentiment largely below the surface.
Many Singaporeans can recall unpleasant experiences involving foreigners, ranging from displays of arrogance at bars and clubs to the unruly behaviour of construction workers.
In 2012, rage against foreigners neared boiling point after a wealthy Chinese national rammed his Ferrari into a taxi, killing himself and two others - including the Singaporean cab driver. The incident sparked much resentment against foreigners - especially wealthy ones.
But very often, the hardliners' vitriol is directed primarily at the government, said Eugene Tan, an appointed lawmaker in parliament and a law professor.
"The foreigners are [just] lightning rods as they are not faceless when compared with the government. Examples of foreigners behaving badly are used in an attempt to illustrate the apparent excesses of those who are in Singapore because of the open immigration policy."
Siew said these incidents "also show how easy it is for valid criticism of government policy to spill over into, or even provide cover for, real xenophobia".
Both Siew and Tan said Singaporeans in general accepted foreigners and that discerning outsiders knew that anti-foreigner sentiment, while more vocal in recent years, was mostly not personal. "Nonetheless, it's a situation that bears close watching since Singapore's hard-earned reputation of being an immigrant-receptive society can easily be undone," Tan warned.