Singapore on Saturday approved 81-year-old S.R. Nathan's application to run for re-election as president and rejected three others, paving the way for him to return unopposed for a second six-year term.
A government-appointed election committee said in a statement that it had issued a single certificate of eligibility to Nathan, a former internal security chief.
"He has all the credentials for the office of the President and is well regarded and respected for his public service," the statement said.
It said the other applicants, Andrew Kuan, Ramachandran Govindasamy Naidu and Ooi Boon Ewe, failed to meet the requirements for the office of president - a post which has custodial powers over the country's huge financial reserves and veto power over government budgets.
Kuan's application was rejected on the ground that the seniority and responsibility of his position as Group Chief Financial Officer of JTC, Singapore's industrial landlord, were not comparable to those required in the constitution.
The businessman had been considered the candidate most likely to meet the strict requirements for the post - a senior position for not less than three years in a government company or a private firm with minimum capital of S$100 million.
When contacted by Reuters, Kuan said he planned to appeal.
"Technically, I qualify. I am extremely surprised about the reason they gave," Kuan said. "I will definitely find an appropriate avenue to appeal."
A political unknown before his surprise bid, Kuan has come under attack over his record at the JTC, a government agency.
On Thursday the JTC, where he was CFO for three years, issued a public statement saying he was asked to resign after an "unsatisfactory" performance. It would not give details.
The presidency has been uncontested since 1993, two years after Singapore's constitution was modified to transform the post to a directly elected one from a government appointment.