It is understood that the shortlist of 19 possible CEC candidates is decided both by the outgoing CEC as well as through a poll of branch chairmen and senior cadres as well as groups like the party's youth and women wings.
The seven names chosen by the CEC are clearly marked out, signalling its choice of the party's core leaders.
According to sources, the seven this round are:
Prime Minister Lee Hsien Loong, 66;
Home Affairs and Law Minister K. Shanmugam, 59;
Health Minister Gan Kim Yong, 59; Finance Minister Heng Swee Keat, 57; Culture, Community and Youth Minister Grace Fu, 54;
Trade and Industry Minister Chan Chun Sing, 49;
and Environment and Water Resources Minister Masagos Zulkifli, 55.
All seven are in the current CEC.
Someone from the CEC will eventually become Singapore's next prime minister, taking over from Mr Lee, who has made clear he intends to hand over to a successor by the time he turns 70, in 2022.
Speculation has been rife over the last year about who his successor will be, with three men touted as front runners: Mr Heng, Mr Chan, and Education Minister Ong Ye Kung, 48.