Amani leader Musalia Mudavadi has asked President Uhuru Kenyatta and Deputy President William Ruto to keep off Nasa affairs.
Mudavadi told the Jubilee leaders to stop piling pressure on the opposition to name its flag bearer ahead of August 8 poll.
The National Super Alliance brings together ODM, Wiper, Ford Kenya and Amani National Congress among other affiliate parties.
Mudavadi told Jubilee to instead concentrate on the promises their regime has not fulfilled to Kenyans.
"As far as we are concerned, there are timelines we must meet before declaring the flag bearer," the Amani leader said.
He said the opposition has its calendar which outlines the steps they will take to ensure they ascend to power after the poll.
"Nasa is not about individuals. It is about the welfare of all Kenyans. We will stick to our national development agenda," Mudavadi said.
"Very soon, we will brief the nation on the latest developments, which are positive," he added.
He spoke after meeting the Kenya Women Parliamentary Association (KEWOPA) at the party headquarters in Lavington on Thursday.
The former deputy prime minister castigated rampant corruption in the Jubilee regime, saying it denied Kenyans critical services.
"The role of the opposition is to check Jubilee's excesses and offer an alternative governance system for Kenyans," said Musalia.
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He also dismissed claims that the Nasa team will disintegrate before the poll.