May said that while she was ready for negotiations set to start 11 days after the June 8 vote, the Labour leader would "find himself alone and naked in the negotiating chamber of the European Union".
Both politicians endured a bruising television grilling on Monday, with May coming under fire from audience members over cuts to public services, including police - an emotive issue following last week's Manchester bombing.
In a speech on Tuesday in Wolverhampton in central England, home to one of the Conservatives' target seats, the prime minister sought to pivot the debate back to Brexit.
"I am prepared. I am ready to go. Jeremy Corbyn is not," said May.
"Only one of us has the determination to deliver the will of the people and make Brexit happen. And only one of us has the plan to make Brexit a success."
When May called the snap election in April, hoping for a stronger mandate for the EU talks, the Conservatives had a lead of more than 20 points over Labour.
But this has fallen back in recent weeks since Labour presented its leftist agenda, and after a row over May's plans for elderly social care that could see many people forced to pay more.
A new Survation poll for ITV television put Labour up three points in a week on 37 percent, while the Conservatives were unchanged on 43 percent. The smaller Liberal Democrats were on eight percent.
On Tuesday, May repeated her Brexit negotiating goals, including withdrawing Britain from Europe's single market in order to control immigration from the continent, and ending the jurisdiction of the European Court of Justice.
And she confirmed once again she would rather walk away than accept a bad deal, saying Corbyn's refusal to do so means "accepting any terms, however unreasonable".
Critics have warned that leaving the EU without a new trade deal in place could cause significant harm to Britain's economy - a position repeated by Labour after May's speech.
"In this election, it is vital that the government is not given a blank cheque for a chaotic, extreme Brexit that would leave our economy... worse off," lawmaker Chuka Umunna said.
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