He contested the April 2019 Senate election in Madrid as candidate of the far-right Vox, commanding votes, short of the votes obtained by the last elected senator. He also ran second in the party list for the 26 May 2019 Madrilenian regional election, and, thus, he was elected member of the regional legislature, as Vox obtained 12 out of the 132 seats up for election. However, Marco refused to assume the parliamentary seat before the inaugural session of the new legislative term citing "health motives".