NASA and Jubilee are currently in a closed-door meeting with the IEBC ahead of the October 26 presidential vote.
Presidential candidates Raila Odinga and Uhuru Kenyatta sent their representatives to the meeting that began at 11.15am on Wednesday.
Jubilee Party secretary Raphael Tuju represented Uhuru while Siaya Senator James Orengo represented Raila at the Bomas meeting.
Journalists were locked out after IEBC chair Wafula Chebukati said it was only for stakeholders.
Earlier, the electoral agency said they were prepared to hold discussions with the two stakeholders.
"We are looking forward to the meeting with Jubilee and NAS today," IEBC said in a tweet.
The electoral commission is to brief Jubilee and NASA on the state of fresh poll preparedness.
The parties are also to agree on seconding their ICT representatives to be enjoined with the commission's officers to oversee the results transmission system.
Previous meetings to unlock the deadlock surrounding the fresh presidential poll flopped, often at the last minute.
NASA canceled a meeting with the commission last week saying it would wait for the Supreme Court's full judgment on the August 8 presidential election. This was delivered on September
The Opposition has insisted it will not be party to IEBC's "cosmetic" boardroom meetings and wants them held in public.
Leaders in NASA said every resolution should be binding.
This comes after police used tear gas on Tuesday to disperse protesters who want IEBC officials sacked before the re-run.
Several volleys of tear gas were fired near the election commission headquarters in central Nairobi.
When protesters regrouped, officers fired more tear gas and beat some with batons. By mid-afternoon calm had returned.
More on this: Police fire teargas to disperse NASA, Jubilee supporters