The two leaders listed the Jubilee administration's achievement, saying it had built roads and constructed the standard gauge railway, among other projects.
Mr Ruto said there was nothing to show for the Sh40 billion allocated to Mombasa County for the past four years and urged residents to vote the current county administration out on August 8.
Mr Kenyatta and the DP said National Super Alliance (Nasa) leaders had been in leadership for 30 years but did not initiate "any" development.
“They are now telling us that they impregnated the railway. Do you people know how a railway is impregnated? Isn’t this a lie?” asked Mr Ruto.
The President and his deputy urged voters in Mombasa to elect Jubilee candidates for governor, senator, woman rep, MP and MCA.
They drummed up support for party candidates Suleiman Shahbal (governor), Hazel Katana (senator), Amina Abdalla (woman rep), Karisa Nzai (Jomvu MP) and Masoud Mwahima (Likoni MP), among others.
Present at the rally were Kwale Woman Rep Zainab Chidzuga, Taveta MP Naomi Shaban and Tourism CS Najib Balala, among other leaders.