The much anticipated Building Bridges Initiative (BBI) rally at Bukhungu stadium, in Kakamega county, could see hundreds of leaders attending.
Although the function has been opposed by sections of Western Kenya leaders, a number of them and colleagues across the country are set to attend.
Orange Democratic Movement party Communication Director Philip Etale on Friday said dozens of leaders have confirmed participation.
"So far 27 Governors, 120 legislators and hundreds of MCAs from across the country have confirmed that they will be joining the people of Western for the BBI rally at Bukhungu Stadium tomorrow #BBIAtBukhungu," he said in a tweet.
Saturday's meeting is the second forum for BBI after the last week event at Kisii, in which Raila Odinga attended.
Police have banned a parallel rally organised by Musalia Mudavadi and Moses Wetangula in the same region.
According to Mumias West Sub County Police Commander Peter Kattam, anyone who will be involved in the meetings will have contravened the law and liable for criminal charges.
"This is to notify you that this office has cancelled your permit to carry out the exercise purportedly scheduled to take place 18/01/2020 at Nabongo Grounds starting 0900hrs due to security reasons," read the police directive, according to Standard.