After the EDSA Revolution, President Corazon Aquino appointed him as Minister of Local Government and Presidential adviser/chief negotiator with the Muslim insurgents in Mindanao. He then was elected Senator (1987–1992). As senator, he wrote the Local Government Code. He tried to become Vice President in 1992. He ran under the Liberal Party with Jovito Salonga running for President. He finished fifth among the vice presidential candidates with 9.9% of the vote. 