Several of the candidates vying to take over from May have said Britain must leave on Oct. 31, without or without a deal. Parliament has repeatedly voted against a no-deal Brexit and Hammond said he did not believe Britain was likely to be heading towards leaving without an agreement.
Hammond said parliament would be "vehemently opposed" to a strategy of leaving without a deal, Reuters reported.
"It would be very difficult for a prime minister who adopted no deal as a policy ... to retain the confidence of the House of Commons," Hammond told BBC TV, adding that he could not personally support a no-deal strategy.