In a previous post, we took a look at the electoral landscape, where Prime Minister David Cameron is fighting for a second term against Miliband. However, while nationwide polls can give us a general idea where things stand, this contest will be decided in the 650 electoral districts (known as constituencies). Whichever candidate emerges with the most votes in each constituency becomes its member of Parliament (MP), so we could see some last-minute tactical voting that's hard to account for even in constituency-level polling.
It's unlikely that either the Conservatives or Labour will hold a majority of seats after May 7, so they'll need to turn to smaller parties to keep them in power. Besides the Tory and Labour numbers, we'll want to keep an eye on a few other parties. The Liberal Democrats have served as the Tories' junior coalition party for the last five years, and their backing of Conservative austerity policies has enraged many left-wing voters. The Lib Dems are all-but certain to lose many of the 56 seats they hold, but it's unclear how deep the damage will be. If there are enough Lib Dems and Conservatives left at the end of the night to keep Cameron in power (possibly with the help of some even smaller parties), we'll probably see another coalition, though it's not impossible that the Lib Dems could ally with Labour this time.
While Labour is certain to gain seats in England and Wales, it's facing massive losses in Scotland to the Scottish National Party (SNP). Miliband won't be happy to lose those constituencies, but the SNP has made it clear that they won't support a Tory government. Miliband has ruled out a formal coalition with the SNP, but it's quite possible we could see a more loose and informal partnership, which we'll explore in greater detail later in this post.
The UK Independence Party (UKIP) is also likely to be a factor on Thursday. UKIP has called for taking the UK out of the European Union in large part to restrict immigration, and it has siphoned votes away from the major parties, particularly the Tories. But while UKIP polls well in England, its support isn't concentrated in any one region, so it's unlikely to win a plurality in more than a handful of seats. The Lib Dems are very pro-EU, so we almost certainly won't see a formal coalition with the Tories, Lib Dems, and UKIP. Still, if UKIP has enough constituencies to keep Cameron in power, we may see some sort of negotiation. Several smaller parties can also play a role, which we explore in more detail here.
Head below the fold for a race-by-race look at the key contests Thursday, and an exploration of what might happen after the election, too.