A new round of Trans-Pacific Partnership (TPP) ministerial meeting kicked off here Tuesday, with key obstacles remaining in the areas of market access and intellectual property to finalize the ambitious Asia- Pacific trade deal.

The TPP, covering about 40 percent of global economy and believed to be the biggest trade agreement in the world in the past two decades, is central to the Obama administration's policy of advancing economic engagement in Asia and writing the rules for international trade and investment in the 21st century.

Talks on the TPP had been stuck for months as other participating countries were reluctant to make major concessions needed to close a deal before the US Congress granted the trade promotion authority, also known as the fast-track authority, to President Barack Obama.

That trade authority would allow the US president to submit trade deals to Congress for an up-or-down vote without amendments, which is crucial for the swift congressional consideration of a TPP deal.

With the fast track authority in hands by the end of last month following weeks of tough fight in Congress, the Obama administration is stepping up efforts to push for an early conclusion of the Asia-Pacific trade pact. Optimism has grown in recent weeks that the four-day ministerial meeting could be the final round of negotiations on the broad TPP agreement.

"I think the TPP ministers are going to Hawaii with the hope that they can finish or substantially complete the negotiations," Jeffrey Schott, a senior fellow and trade expert at the Washington- based Peterson Institute for International Economics (PIIE), told Xinhua in an interview.

Schott said there are "only a small number" of outstanding issues in the TPP trade talks, but they are "generally the most difficult, the most complex, or the most political sensitive", citing examples of rules on the intellectual property, discipline on the state-owned enterprises, labor and environmental provisions, and the investor-state dispute settlement.

One of the highlights of the ministerial meetings is whether the United States and Japan, the two biggest players in the TPP, could complete their bilateral market access negotiations of agriculture and autos, which had stalled overall TPP trade talks.

US Trade Representative Michael Froman is expected to meet Tuesday with Japanese Economic and Fiscal Policy Minister Akira Amari to try to resolve the remaining sticking points in bilateral talks, including the US demand for an increased access to Japan' s rice market.

"It's my understanding that the US and Japan paralleled negotiations will close simultaneously when the TPP closes because they're linked to the TPP deals," Tami Overby, the US Chamber of Commerce's senior vice president for Asia, told Xinhua.

Overby said the United States and Japan are very close to make a deal, but "it would be not possible" for the two sides to conclude bilateral negotiations until the overall TPP deal does.

The US and Japan are waiting for other countries to engage in market access negotiations before taking the final step, according to trade experts. In particular, Canada hasn't come forward with an offer on the market access of dairy products as Canadian Prime Minister Stephen Harper faces re-election in October.

A bipartisan group of US lawmakers have warned that it would be hard for them to support Canada's inclusion in a final TPP deal if Ottawa would not significantly open its market to more dairy imports.

In terms of rules on the intellectual property, the big question of whether other TPP countries will agree to the US demand for 12 years of data protection for biologic medicines is still up in the air, according to US political news website Politico.

Other countries have pushed back the US demand and voiced concerns that the US might use it as a vehicle to extend drug company monopolies over expensive biologic drugs.

"What we do need is to ensure that we all rise to the same place, the same high standards of a comprehensive agreement that will create the right eco-system so that countries can develop their own IP (intellectual property)," said Overby.

The Obama administration is under pressure to seal a TPP deal and get it passed in Congress as soon as possible, securing the president's trade legacy before the 2016 US presidential campaign heats up.

Australian Trade Minister Andrew Robb warned Sunday that failure to reach a TPP deal this week could delay an agreement for years due to elections in the United States and Canada.

The talks this week "are very important, partly or mainly because of the political cycle in the US and also an impending Canadian election," Robb said in an interview with the Australian Broadcasting Company. "If we don't do it this week things are going to be very difficult I think to conclude it within a couple of years."

The TPP talks involve Australia, Brunei, Canada, Chile, Japan, Malaysia, Mexico, New Zealand, Peru, Singapore, the United States and Vietnam.