Former defence secretary Liam Fox was eliminated from the contest after winning the support of just 16 MPs. Work and pensions secretary Stephen Crabb, who received 34 votes, withdrew from the race afterward and backed Ms May
Ms May’s tally amounted to exactly half of the 330 Conservative MPs, but was a majority of the 329 voting, guaranteeing her a place in the final run-off ballot of Conservative members unless she loses supporters to one of her rivals over the next few days.
Now attention turns to the battle for the second place on the ballot paper, with leading Brexit backer Andrea Leadsom taking 66 votes and Eurosceptic justice secretary Michael Gove 48.
The remaining contenders are due to face a second MPs’ vote tomorrow, followed by a final round next Tuesday unless any of the candidates has dropped out by that time.
The two who top the final round of MPs’ votes go to a postal ballot of party members to select a new Conservative leader — and prime minister — in a contest due to end on September 9.
Ms May said: “I am pleased with this result, and very grateful to my colleagues for their support.
“There is a big job before us: to unite our party and the country, to negotiate the best possible deal as we leave the EU, and to make Britain work for everyone.
“I am the only candidate capable of delivering these three things as prime minister, and tonight it is clear that I am also the only one capable of drawing support from the whole of the Conservative party.”
Her dominant first-round performance and energy minister Ms Leadsom’s strong showing in second place will put intense pressure on Mr Gove to stand aside.
Despite her overwhelming support among MPs, Ms May will be all too aware that in the two previous contests conducted under the present rules, initial frontrunners Kenneth Clarke and David Davis went on to be rejected by grassroots members.
As a supporter of the Remain vote in last month’s EU referendum, Ms May is vulnerable to claims by Eurosceptic rivals that the largely Brexit-backing membership requires a leader who actively campaigned to Leave.
And she has faced criticism over her refusal to give firm assurances that EU nationals would be allowed to remain in the UK and was accused by former cabinet colleague Ken Clarke of being a “bloody difficult woman” with little knowledge of foreign policy.
Mr Gove’s proposer, Nicky Morgan, said he was winning the support of Leave campaigners who want a “heavyweight” representative in the race.