LONDON — Britain’s record-breaking heat wave came against the backdrop of an intensely watched national political contest, as the race to succeed Prime Minister Boris Johnson was winnowed to just candidates ahead of a critical vote on Wednesday.
Rishi Sunak, the former chancellor of the Exchequer; Penny Mordaunt, a middle-ranking trade minister; and Liz Truss, the foreign secretary, remain in the contest for the support of Conservative Party lawmakers who will on Wednesday narrow the field to two.
They will then battle for the votes of Conservative Party members, with the result of the leadership contest scheduled to be announced on Sept. 5. Under the British political system, the winner becomes prime minister because the Conservatives hold the biggest bloc of seats in Parliament.
The results of the latest ballot of Conservative lawmakers, held and announced in Parliament on Tuesday, put Mr. Sunak firmly in the lead with 118 votes, just short of the 120 he needs to secure his place in the shortlist of two on Wednesday.
The battle for second place remains wide open, with Ms. Mordaunt securing 92 votes — an increase of 10 after a similar vote on Monday — and Ms. Truss just behind with 86. Ms. Truss holds slightly more momentum, having won 15 more votes in the latest round.
The fourth-placed candidate on Tuesday, Kemi Badenoch, the former equalities and local government minister, was eliminated from the contest after a campaign that raised her profile. Supporters of Ms. Badenoch will probably decide the outcome of Wednesday’s contest, as the 59 votes she amassed on Tuesday are redistributed among the remaining contenders.
In theory, any of the three of the surviving candidates — Mr. Sunak, Ms. Mordaunt and Ms. Truss — could make it to the final two at the end of the least predictable contest of its type in recent memory.
Because the ballot is secret, some lawmakers have been rumored to have voted strategically, to try to eliminate candidates they dislike, rather than to promote their favored one. Other legislators may have been swayed by promises of future jobs by the candidates.
And while Mr. Sunak has emerged as the clear front-runner to reach the final round, he would face an uphill battle there. According to one opinion poll, both Ms. Mordaunt and Ms. Truss are more popular than Mr. Sunak among Conservative Party members.