The proposed amendment was passed by the Senate on May 1 on a 40-19 straight party-line vote, exceeding the required three-fifths majority. Before going to voters for final approval on the November 2020 ballot, the amendment must pass by the same margin in the House, where Democrats hold 74 seats. With Republicans unified in opposition, they’ll need all but three of their members to vote in favor of the amendment, which would do away with a constitutionally mandated flat tax.