He took an active part in the liberal politics and was appointed, after the Liberal Revolution of 1820 in Porto as a Member of the Provisional Regency of the Government of the Realm, then instituted (merged later with the one of Porto). Withdrawn in 1823 from the public businesses, after the Vilafrancada he returned to the political activity when, in 1826, the Constitutional Charter was sworn, under the Regency of Infanta Isabel Maria of Portugal, becoming part, as 24th Secretary of State of the Treasury Affairs or Minister of the Treasury, of a constitutional government, in which Saldanha was Minister of War. Miguel's coup, proclaiming himself King, withdrew him again from politics. In 1833, after the victory of the liberal forces, he was appointed Member of the Commission created to take knowledge in charge of the study of the state of the consolidated external debt, etc., on 18 July 1838. He also became a Peer of the Realm in 1835, Honorary Minister and Counselor of State and Commander of the Order of Christ.