The House of Commons Speaker John Bercow will this afternoon select the options to be voted on from a selection of 16 put forward by MPs on Tuesday.
MPs will then select one, or more, of the options they are in favour of on a ballot paper, with results expected at some point after 21.15 GMT.
The votes are technically non-binding, but could put huge pressure on May to change course. If there is a majority for any option, MPs could also choose to legislate for it to force the prime minister to act.
So what will the likely options on the ballot paper be and how will MPs vote?
No-deal Brexit
Even if selected by Bercow, this option is highly unlikely to be successful given that MPs have repeatedly passed previous motions ruling out a no-deal exit.
Chance of passing today: 0%
Revoke Article 50
Chance of passing today: 5%
A confirmatory second referendum
Chance of passing today: 20%
Staying in the Customs Union
A very soft Brexit
The Labour leadership's own motion is broadly in line with this. However, there are signs that the party may also throw its weight behind a backbench motion brought forward by Labour and Conservative pro-Europeans for a "Common Market 2.0" or "Norway Plus" relationship with the EU. This option would leave Britain very closely tied to the EU and could potentially command a majority of MPs.
However, with most Conservative MPs opposing and Labour deeply split between those in Leave seats who object to the plan as a betrayal of the referendum result and Remainers who are holding out for a second referendum, this option is likely to fail to win a majority at least at the first time of asking.
However, if plans go ahead for another run-off series of indicative votes next week in which the best losers from today's votes are voted on again then it could potentially squeak by, particularly if it is judged as the best option for preventing a no-deal Brexit.