Boris Johnson faces a hugely important verdict from voters on Thursday as the Conservatives defend seats in Wakefield and in Tiverton and Honiton, with a double defeat likely to reignite speculation about a new challenge from Tory MPs.
The byelections were called after the respective MPs resigned in disgrace. Imran Ahmad Khan stepped down in Wakefield having been convicted of sexually assaulting a teenage boy, while Neil Parish quit in Tiverton and Honiton after watching pornography in the Commons.
The West Yorkshire seat had been safely Labour before Khan took it for the Conservatives in 2019, and Labour is the clear favourite to win on Thursday. The Devon constituency, in contrast, is seen as neck-and-neck between the Conservatives and the Liberal Democrats, despite the seat in its various forms having been strongly Tory for more than a century.
Parish won in 2019 by a majority of more than 24,000. If the Lib Dems win, it is being billed as the biggest majority ever overturned in this way, although there have been higher percentage swings.
Losing Tiverton and Honiton would be likely to particularly worry Conservative MPs given not just the size of the majority but also that it would be another rural, Brexit-minded Tory stronghold to shift to the Lib Dems in less than six months. In December the Lib Dems took North Shropshire, overturning a Tory majority of nearly 23,000 after the former MP, Owen Paterson, quit over a lobbying scandal.
In June last year the Lib Dems won another formerly very safe Tory seat, Chesham and Amersham, a so-called blue wall commuter-belt constituency to the north-west of London.
Lib Dem campaigners have said Tiverton and Honiton is seen as winnable but they worry that a number of disaffected Conservative voters will stay at home rather than transferring their support.
While Labour and the Lib Dems are fielding candidates in both seats and have made no pact, there has been an implicit understanding that each party would concentrate resources in Wakefield and in Tiverton and Honiton respectively, so as to boost their chances of victory.
This month sustained pressure on the prime minister over lockdown-breaking parties in Downing Street and worries about a sense of drift in government led to a confidence vote in which 148 Tory MPs tried to oust Johnson and 211 backed him.
While ministers sought to present this as a resounding endorsement, Johnson did worse than Theresa May when she faced a similar vote, with 41% of his parliamentary party wanting a new leader.
Under Conservative party rules, the win gives Johnson a 12-month immunity from challenge, but these could be changed if there is sufficient appetite for it among Tory MPs. This seems unlikely in the short term, but rebel MPs would see a double byelection loss as a significant setback, which could mean a renewed effort to unseat Johnson in the autumn.
Johnson has sought to reset his premiership with a focus on issues that give him the opportunity to please his core voters, including battles with lawyers over deporting asylum seekers to Rwanda, changing human rights rules, and trying to blame Labour for rail strikes.