The UK doesn't a have two-party system, it has a multi-party system, but there are similarities between the mainstream left party (Labour) and the Democrats, and the mainstream right party (Tories) and the Republicans.

In a recent by-election in the Labour stronghold of Rotherham, Labour managed to hold on to the seat, but the nationalist (BNP, UKIP)parties did better than the mainstream conservatives. That means that what were third, fourth, and even fifth parties are now coming in second and third.

Rotherham By-Election: Labour Secures Victory

Labour wins three by-elections on a night that saw a surge in support for UKIP and dismal results for the Tories and Lib Dems.

9:07am UK, Friday 30 November 2012

Labour has held onto Rotherham in a parliamentary by-election which saw a surge towards the UK Independence Party (UKIP) and disastrous results for both coalition parties.

The Conservatives finished fifth behind not only UKIP but also the British National Party and Respect, while Tory candidate Simon Wilson only held onto his deposit by a whisker.

Liberal Democrat Michael Beckett came eighth and lost his deposit, trailing behind the English Democrats and an independent.

Labour's Sarah Champion won comfortably with 9,866 votes, a majority of 5,218 (24.46%) over UKIP.

The party's majority in a seat it has held since 1933 was marginally down on the 27.9% it recorded in the 2010 general election.[More]

If mainstream conservatives don't like losing out to fringe parties, they should consider not betraying their countries. This is an option that may not be available to the Left, which really does depend on immigrant votes, and would give conservatives a competitive advantage. For more detailed analysis, see After Rotherham, Ukip is now a national populist party – a magnet for anger at the British establishment, By Tim Stanley in today's Telegraph.