Its a toss not like 2017 where Luo,Kamba and Mijikenda were united.
Depends how they play the politics. In 2013 Joho won with 132K against Shahbal 95K. Joho and Shahbal were in the same team and the politics of Arab vs Bantu Swahili played out. Shahbal got Kambasa and Joho got Luos ,Swahilis and Mijikenda.
Nasir candidature will bring out this rivarly again. And Sonko being Mbara might get the GEMA vote which in 2017 was around 100K.
Hassan Omar should let Nassir snd Sonko even out . Safeguard The UDA votes campaign on a platform a vote for him is a vote for Ruto otherwise just like it happened in Nyali in 2013 GEMA might vote for Sonko as they voted for Awiti Bolo in Nyali in 2013.
Why Giriamas are not aggresive in Mombasa no one knows. They have substantial number of votes.