Wiper Party leader Kalonzo Musyoka now wants President Uhuru Kenyatta to include Amani National Congress (ANC) party leader Musalia Mudavadi and Ford Kenya leader Moses Wetangula in the national unity talks.
Kalonzo said the unity and reconciliation talks will be more meaningful if all leaders are included.
The Wiper leader warned that the unity process could stall if President Kenyatta and former Prime Minister Raila Odinga sideline other leaders.
"The President must invite all leaders on the negotiation table if he wants to leave a good legacy and achieve his reconciliation agenda," he said during a briefing with journalists in Mwingi Town on Sunday.
Kalonzo said the exclusion of other leaders in the unity talks is sending a wrong impression and could stall the process.
The former Vice President who has since declared support for the Jubilee government's development agenda asked Wetangula and Mudavadi to soften their stand and work with the government.
Kalonzo said that supporting the government does not mean that they have neglected their opposition role.
"We are still actively in opposition and our work with Jubilee does not mean we have abandoned our roles," he said.
Kalonzo said that the decision to work with the Jubilee government is aimed at fast-tracking electoral reforms and justice.
The Wiper leader declared support for Uhuru's government last week amid claims that he could be appointed to the Cabinet.
There are also claims that Mudavadi could also be appointed in President Kenyatta's government as talks emerge of a looming cabinet reshuffle.
However, State House spokesperson Kanze Dena on Monday denied the reports, saying she was not aware of the changes.
On Sunday, Mudavadi said that he supports the handshake so long as it is structured and aims at pushing for electoral reforms.
Mudavadi who spoke to NTV said that his party will remain in opposition and play the watchdog role.