"There is a certain sense of nervousness in the air and the stakes are high for the PAP," Ho Khai Leong, a political analyst at Nanyang Technological University, said.
"If the opposition wins more seats, it will spark off a trend; more professionals will join the opposition," he
"If more professionals join the opposition camp then, in a few more elections, the PAP may not be able to keep its dominance in parliament," said Ho
.The 20 new names fielded by the Workers' Party, the oldest opposition party, included many with careers as academics, lawyers and bankers - a far cry from previous line-ups.
The opposition has fielded candidates for more than half the seats in parliament, denying the PAP an automatic victory on Nomination Day for the first time in nearly two decades.