Here's a guide to what the House of Commons is voting on, and how different politicians are trying to re-write the government motion
Just 18 days before the United Kingdom is due to leave the EU on March 29, there is still no ratified divorce deal and talks with the bloc have stalled
Sunday Times says Brexiteers are pushing for May to quit
Implied volatility in the pound-dollar pair touched the highest since mid-January on Friday, as traders sought to hedge against price swings
While the European Commission said "no solution" was in sight as British ministers left Brussels after talks on Wednesday, UK has claimed that "reasonable" proposals to satisfy British MPs' concerns
The voting process could take hours, and most of the drama takes place out of sight of television cameras
Just a few weeks remain before Britain is due to leave the European Union at the end of March
While the votes on Wednesday will not be on May's withdrawal agreement, which is scheduled by March 12, they could influence some aspects of the Brexit process
After MPs rejected her withdrawal deal last month, May is seeking ways to address their concerns about its most controversial element, the so-called Irish backstop clause
In the tortured history between the two island nations, Brexit is just the latest in a long line of perceived slights the Irish have suffered at the hands of the British
The UK government called meetings in recent weeks as Brexit jeopardises the already depleted number of workers needed to dig up roads and overhaul the country's out-of-date broadband network
The latest migration figures show workers from the rest of the EU are now already leaving the U.K. in droves
With only 37 days until Britain leaves the EU, its biggest foreign and trade policy shift in more than 40 years, divisions over Brexit are redrawing the political landscape.
Though the full implications remain unclear, the split has the potential to complicate Prime Minister Theresa May's task of getting her deal with Brussels through Parliament
The EU maintains the so-called backstop, a guarantee in the Brexit deal which binds Northern Ireland closely to the bloc, is needed
Businesses and the EU's executive have ramped up planning for a no-deal Brexit
Prime Minister Theresa May is also expected in Brussels next week, but he visit has not been confirmed
UK farmers export about a third of the lamb they produce, and almost all of that heads to the EU, particularly France and Germany
Lawmakers defeated the government 303-258 on the main motion asking them to reaffirm support for her plan to seek changes
The state's dominance makes negotiating free-trade agreements much easier than it would be in a post-Brexit UK