Conservative leadership candidates Boris Johnson and Jeremy Hunt are preparing to face off for what’s expected to be the final time.
They will take part in a debate, hosted by The Sun and talkRADIO, in front of a live studio audience in London.
The debate has special importance as many Conservative Party members are yet to return their ballot.
It is believed votes are coming in more slowly than expected as party members are waiting to see how the candidates perform during the campaign.
Last week's debate was dominated by the leak of diplomatic comments from Britain’s ambassador to the US, Sir Kim Darroch, which described the Trump White House as “inept”.
MPs and senior civil servants accused Mr Johnson of metaphorically throwing Sir Kim "under the bus" for failing to back the ambassador in the days before his resignation.
The leadership frontrunner has moved onto other issues, and said he would like to offer “preferential” tax treatment to companies that look after their staff.
He said: “It is time for the Treasury and the NHS to work together to review the rules.”
“We should put it into effect this autumn in what, if I am lucky enough to be elected, would be the first budget of the new Government.”
He added: “Yes, of course all tax breaks cost money. But any loss in revenue would be more than made up by the gains in productivity and the savings in NHS spending.”
Meanwhile, Mr Hunt has travelled to Brussels for a meeting of EU foreign ministers in a bid to prevent the collapse of the Iran nuclear deal.
He said: “I'll be building on the leadership shown by the UK, alongside France and Germany, as we do what it takes to maintain the nuclear deal, and to work to encourage Iran back into compliance.”