Do incumbents in Labour party leadership elections need the support of 35 MPs?

Question

When Jeremy Corbyn announced his Labour leadership candidacy in 2015, many believed he would fail to get the support of 35 MPs needed to stand for leader.

Currently, a significant portion of the Parliamentary Labour Party are trying to force Corbyn to step down. Supporters point out he stil has popular support among party members, and would easily win another leadership election.

Clearly, there is a wide discrepency in the preferences of the Labour party base, and the preferences of its MPs. Would Corbyn as the incumbent need the support of 35 MPs, if he were to run again for leader, should there be a new election?

Answer 1

Under the current rules a new candidate for the Labour leadership requires the support of 20% of Labour MPs and MEPs (members of the European parliament). This would equate to 50 signatures from 230 MPs and 20 MEPs. There appears to be some uncertainty as to whether this is also true for an incumbent. The difficulty apparently comes down to rule Rule 4.2.ii of the Labour party rule book which states that when a party leader faces a challenge “any nomination must be supported by 20 per cent of the Commons members of the PLP. Nominations not attaining this threshold shall be null and void” but doesn't make clear whether this applies only to the challenger(s) or not.