In the run-up to the US presidential election in 2000 between George W. Bush and Al Gore, the Washington Post’s legendary columnist EJ Dionne wrote: "There is no Catholic vote. And yet, it matters."

The reason there is doubt around the existence of a unified Catholic vote is that such a voting bloc is far too diverse to pin down to a particular set of voting habits or priorities.

Catholics make up 23 per cent of the US population and are divided along various ethnic and social lines. White Catholics vote in decisively different ways to their Latino counterparts, while regular Mass-goers are much more likely to vote for the Republican Party – often referred to as the GOP, standing for its nickname of Grand Old Party – than their non-attending co-religionists.