Does John Mellencamp support or oppose same-sex marriage?

Sir Elton John previously favored civil unions and made critical statements of those who were holding out for full marriage equality. Now, however, with the legalization of same-sex marriage being seriously considered by the UK government, Sir Elton is now saying civil partnerships are not equal and is fighting for marriage. He is openly gay and in a civil partnership with David Furnish (who is therefore technically a "Dame", but is more accurately referred to as "the Honourable David Furnish"). John and Furnish married on the first day that civil unions became legal in the UK.