A TPP pact – the partnership involves 12 nations: United States, Australia, Brunei, Canada, Chile, Japan, Malaysia, Mexico, New Zealand, Peru, Singapore and Vietnam – would create a "mega-regional" bloc with a combined gross domestic product (GDP) of $28 trillion, according to Reuters. That will make a TPP pact the most sweeping trade deal in a generation and a legacy-defining achievement for U.S. President Barack Obama, whose administration has been advocating a pivot to Asia.

Held from July 28-31 on the island of Maui, the TPP negotiations fell short of a deal due to clashes over dairy and automotive trade, as well as a standoff over biologic drugs made from living cells, Reuters reported, citing sources involved in the talks. According to the newswire, the sticking point on autos related to the rules on deciding the origin of cars, which would impact whether a car was subject to duties. On drugs, the U.S. wants the data used to create biologic drugs protected for 12 years, while other countries argued for less.

"But at the same time, I'm cautiously optimistic there's enough self-interest from each of the countries involved. There [will be] so much to be gained if we can get this done and put into place [over] the next 12 months," the 61–year-old who was the U.S. trade representative from 2009 to 2013, said. During his four years at the helm, Kirk focused mainly on U.S.' trade policies such as the Anti-Counterfeiting Trade Agreement (ACTA) and TPP treaties.

"I've been in these negotiations and I know the worst thing to do is to put an artificial timeline on it," Kirk, the former Democratic mayor of Dallas and once America's chief trade negotiator, said in an exclusive interview with CNBC at the weekend.

Despite the failure of the latest Trans-Pacific Partnership (TPP) talks in Hawaii, a conclusion of the potentially world-changing trade pact remains on the cards over the next 12 months, said former U.S. trade representative Ron Kirk.

At the moment, almost 90 percent of the vast Pacific free-trade agreement had been negotiated, Kirk said, leaving the talks in the "difficult, final stages of a marathon."

"Get 12 of your family members to a restaurant and say 'can we all agree to order the same thing?' That [isn't going to] happen, so imagine bringing together 12 countries of different stages of development.

"But rather than focusing on what we haven't done, I am encouraged that we're 90 percent of the way there," Kirk said. "My friends who run marathons remark the worst phase of the run is the last two to three miles. We've run nine-tenths of this race and … I'm hopeful that the benefits will outweigh the difficult issues and get us across the finish line."

U.S. Secretary of State John Kerry echoed this confidence last Friday. Speaking to reporters on his visit to Vietnam to mark the 20th anniversary of diplomatic relations, Kerry said that given the good progress made in Hawaii, the TPP could be completed before the end of 2015.

However, Japan showed less optimism about the trade deal that's already eight years in the making.

According to the Japan Times, Economic and Fiscal Policy Minister Akira Amari said it would be difficult to reconvene a meeting of TPP trade ministers by end-August and with the schedule for a next ministerial meeting up in the air, Japan is unlikely to wrap up domestic ratification procedures for the regional trade deal by the end of 2015.

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Meanwhile, New Zealand Prime Minister John Key told CNBC at the weekend that the TPP could be finalized this year, even though there was the possibility that negotiations could continue into 2016.

"There is a window of opportunity to close TPP and I think if you don't get that done soon, one of the problems you've got is you're going to run into the U.S. presidential election campaign and it will be more controversial and difficult to bed down," Key said.

"It's already difficult for the Canadians because Stephen Harper has an election on October 14... but I remain very firmly of the view that a deal will be completed."

Canada's refusal to accept more dairy imports has been a major sticking point and the U.S. and New Zealand have said they will not sign a deal that fails to open new dairy markets. Canada's ruling Conservatives fear a backlash in October's federal elections if they cut protections for dairy farmers and allow in more imports, according to Reuters.

But New Zealand's Key stood firm on the country's call for Canada to open up its dairy market.

"I'd say we're ambitious - not only for our country, but for a successful and quality TPP. Anyone can do a deal, but if it's low quality then in the end it doesn't take you very far. Now, I don't mean you're going to get utopia, but I think if we lack ambition then while we will be able to get to a signing ceremony, the practical effects for our economies will be heavily diluted," he told CNBC.