The Singapore prime minister’s estranged brother on Wednesday said he has joined an opposition party ahead of elections next month, presenting a new challenge to the country’s long-ruling government.

The city-state’s parliament was dissolved on Tuesday for a general election on July 10, even as the country struggles to recover from a major coronavirus outbreak that hit migrant-worker dormitories particularly hard.

Lee Hsien Yang is locked in a long-running row with his sibling, Prime Minister Lee Hsien Loong, over the legacy of their father, Singapore’s late founding leader Lee Kwan Yew.

The 62-year-old met with Tan Cheng Bock, the leader of new opposition group Progress Singapore Party (PSP), on Wednesday morning and revealed that he had recently become a member.

“I joined the party because I think that [Tan] is committed to doing the right thing for Singapore and Singaporeans, and he loves the country and has brought together a group of people who share his vision,” he told reporters.

He would not be drawn on whether he planned to run as a candidate in the election.

Tan, a popular figure who was once a lawmaker with the ruling People’s Action Party (PAP), said Hsien Yang was “not just an ordinary person”.

“His father is the founder of Singapore, so that’s very important,” he said.

The PSP, launched last year, will not threaten the PAP’s decades-long hold on power but the combination of a Lee family member and Tan could draw some voters away from the ruling party, observers believe.

Mustafa Izzuddin, senior international affairs analyst at management consultancy Solaris Strategies Singapore Pte Ltd, said the move “helps to boost the chances of PSP doing well in the elections”.

“Whether that translates into votes . . . will depend on many other factors, not just him joining the party,” he said.

Mustafa said if he decides to run as a candidate, “it will create an even greater political buzz” and the party would have a chance of winning in the district where he is fielded.

There is speculation that if he does run, it might be in his father’s former constituency on the fringes of the business district.

Lee Hsien Yang, a business executive, and his sister Lee Wei Ling fell out with their prime minister brother following the death of their father in 2015.

The family row centres on allegations made by the premier’s siblings that he is seeking to block the demolition of a family bungalow to capitalise on Lee Kuan Yew’s legacy – something the prime minister has denied.