Labour MPs voting on a motion of no confidence in the leader Jeremy Corbyn, as another party frontbencher quit their post.
The secret ballot comes after Mr Corbyn told supporters at a rally outside Parliament to not “let those people who wish us ill to divide us”.
Shadow justice minister Andy Slaughter is the latest to leave his post, after a series of shadow cabinet departures.
Shadow chancellor John McDonnell said Mr Corbyn was “not going anywhere”.
