Bush calls for ban on same sex marriages 2006-06-04 HKT 07:45 President Bush has called for a constitutional amendment to ban same-sex marriages. Mr Bush used his weekly radio address to deliver a plea for the US Senate to formally define marriage as the union of man and woman. He said the measure was needed because "activist courts" left no alternative. Amending the US Constitution requires approval by two-thirds of the House of Representatives and Senate and three-fourths of the 50 state legislatures. Lawmakers say the amendment is unlikely to pass.