Voters back same-sex marriage Voters back same-sex marriage The passions of grass-roots Tories who are bitterly opposed to same-sex marriage are not shared by the wider electorate. Most voters back a change in the law - and very few opponents are willing to switch their votes because of this issue. However, as MPs gather to debate the bill on same-sex marriage, perhaps the more significant figure is that only 7% include it among the top issue that will determine their vote. We offered people a list of 15 topics and asked them to pick up to four. Same-sex marriage comes twelfth. And those who DO include it divide 58-42 in being more likely to support a party that backs a change in the law. So, among the public as a whole, 4% are pro-same-sex marriage AND say this is a vote-deciding issue, while 3% are in the opposite camp. Among those who voted Conservative in 2010, just 6% say this is a vote-deciding issue, and they divide 3-1 against same-sex marriage. So even there, the net effect is tiny.