Boris Johnson’s Conservatives are giving him the benefit of the doubt after his former chief adviser declared he was unfit to lead the country out of the pandemic. But ministers fear the British prime minister will face a bigger battle with his party if the coronavirus variant first detected in India derails his plan to lift restrictions next month.

Officials are now intensely studying data on the new strain, which they estimate has seeded across most of the country and accounts for as many as three-quarters of all new infections. It also appears to be more transmissible than the previously dominant one that took hold late last year and led to another lockdown. Cases of the new variant have been doubling each week and more people are requiring hospital treatment.

While Britain has steamed ahead with its vaccination program, there’s a growing sense of deja vu. A delay to ending the last of the lockdown measures would be a blow for Johnson at a critical time for his credibility as a leader. It would also threaten to puncture the economic optimism that has come with inoculating almost 60% of the population.