This week, voters in the United Kingdom went to the polls and decided strongly against a referendum on switching federal elections to alternative voting, or “AV,” also known as “instant-runoff voting” (IRV). From the BBC:

UK voters have rejected a change to the voting system, a blow to Lib Dem leader Nick Clegg after heavy election losses.

Counting continues but more than 9.8m people have voted to keep first-past-the-post, more than 50% of votes cast.

The No campaign is on course to get 69% of the vote. Mr Clegg said it was a “bitter blow” but he had to accept the “overwhelmingly clear” result.

Currently, the UK House of Commons elections use basically the same system America uses for the House of Representatives: “first past the post.” Within a district, whichever candidate wins the most votes wins the seat, regardless of how few votes they get. What this means is that, in  countries like the UK or Canada, vote splitting among multiple political parties can produce a party that wins a large governing majority with less than 40 percent of the popular vote.

Under alternative voting, people would mark their second and third choices. If no candidate gets 50 percent, the last-place candidate would be dropped, and his or her votes redistributed to those voters’ second choices. This would continue until one candidate finally got over 50 percent.

A tactical mistake for the Liberal Democrats

Agreeing to this referendum was a big concession the Conservatives gave to the Liberal Democrats last year to get them to sign on to a coalition government. Voting reform is hugely important to the Lib Dems because, as the third-largest party, first-past-the-post voting results in their share of seats being radically smaller than their overall share of the popular vote.

The defeat of the referendum is disappointing, especially because when the referendum was first agreed to last year, switching to alternative voting was popular.  It would likely have been approved if put to the voters right away.

In retrospect, the design of this deal was a massive tactical mistake made by Lib Dems and an historically bad political move. By forming a coalition with the Conservatives for a year before the vote, the Liberal Democrats gave the Tories the ability to pursue some very unpopular legislation. These unpopular actions tainted the Lib Dems, and made the idea of coalition governments much less popular. This, in turn, helped make alternative voting unpopular, because it was seen as a way to help the Lib Dems and increase the likelihood of coalition governments in the future.