We've seen this before -- fixation on redefining marriage carries with it political costs:

The Scottish National Party (SNP) will lose support for its goal of independence by backing same-sex marriage, the Catholic bishops of Scotland have predicted.

A new political survey finds that 11% of voters will be less likely to favor independence if the SNP moves forward with its bid to legalize same-sex marriage. Only 3% of voters said they would be more likely to support independence in that event.

Thus the campaign for same-sex marriage is “a massive vote loser which will only alienate many electors,” observed Peter Kearney, a spokesman for the Scottish hierarchy. He encouraged SNP leaders to recognize that the issue is an “electoral liability” as well as an injustice. -- Catholic Culture World News