How the votes may go
Prime Minister David Cameron has always insisted he would not hold a second vote on Syria unless he was confident he would win.
Here we look at how the numbers are likely to stack up.
:: Could Mr Cameron win the vote with support from his own party alone?
The Government has a working majority of 17 and around 10 of the 330 Tories are expected to rebel. But Mr Cameron has made it clear he wants a broader consensus before expanding air strikes into Syria. Former shadow home secretary David Davis and defence committee chairman Julian Lewis are among the Tories preparing to oppose the motion but some of the MPs who rebelled in the 2013 vote are expected to support the Prime Minister this time, including Foreign Affairs Committee chairman Crispin Blunt, Sarah Wollaston and Charles Walker.
:: How many of Labour's 231 MPs are expected to back the Government?
The prospect of bombing in Syria has proved toxic for the already deeply divided Labour Party under Jeremy Corbyn. MPs are being given a free vote after the Labour leader was forced to drop his plans to whip the parliamentary party into opposing intervention. Up to 50 Labour MPs are expected to back the Government including the shadow foreign secretary Hilary Benn, who will wind up the debate in Parliament for the party by putting the opposing case to his leader in a messy compromise. Mr Corbyn's deputy Tom Watson has said there is a "compelling case" for action and former shadow minister John Woodcock has said he will vote in favour.
:: What about the Scottish National Party?
Scotland's First Minister Nicola Sturgeon has said her party in Westminster, which currently has 54 MPs after two lost the whip, will vote against the motion.
:: And the smaller parties in Parliament?
The Liberal Democrats - who now have just eight MPs - have decided to vote in favour, as has the Democratic Unionist Party, also with eight, and the Ulster Unionist Party's two MPs are also expected to back intervention.
Plaid Cymru and the SDLP, along with Green Party MP Caroline Lucas are all set to oppose the motion.