MANILA, Philippines (AP) — The Trans-Pacific Partnership trade deal between the U.S. and 11 other Pacific nations is drawing potential new members from Asia and criticism from those excluded, as it heads for a tough ride in the U.S. Congress.

Leaders of the trade grouping that spans the Pacific Rim met alongside a regional economic summit on Wednesday in the Philippines and President Barack Obama urged them to ratify the deal "as quickly as possible."

The leaders issued a statement acknowledging interest among other countries in joining the pact, which currently represents about 40 percent of global trade.

"This interest affirms that through TPP we are creating a new and compelling model for trade in one of the world's fastest growing and most dynamic regions," the statement said.

Philippine President Benigno Aquino III, host of the Asia-Pacific Economic Cooperation meeting in Manila, met with Obama and sought his help in eventually joining the accord, which aims to reduce barriers to trade and also set labor and environmental standards.

"If the whole idea is to broaden trade, making it exclusive actually defeats the whole purpose of why you enter into all of these agreements," Aquino said earlier in the week.

Indonesia and South Korea are among other countries that have expressed interest in joining the trade arrangement, which is envisioned as a foundation for an even bigger region-wide trading bloc.

The Pan-Pacific trade deal has drawn criticism, however, from China and Russia, which are not part of it.

Russian Prime Minister Dmitry Medvedev said Wednesday that world trade rules should be drafted within the framework of the World Trade Organization, not regional groupings.

Chinese President Xi Jinping also alluded to the potential conflict between regional deals and global trade rules.

"We need to encourage equal footing participation and extensive consultation and make free trade arrangements open and inclusive to the extent possible," Xi said in a speech.

U.S. officials have insisted the trade pact will be open to other countries, as long as they are willing to commit to its rules.

"We welcome China, we welcome Russia, we welcome other countries who would like to join, as long as they want to raise the standards and live up to the highest standards of protecting people and doing business openly and transparently and accountably," Secretary of State John Kerry said in a Nov. 2 interview with the Russian TV network Mir, according to a transcript posted online by the State Department.

Still, ratification of the deal by the U.S. Congress is not certain.

Australian Prime Minister Malcolm Turnbull, whose recently ousted predecessor Tony Abbott strongly supported the agreement, said after Wednesday's meeting that the biggest cause for concern appears to be gaining ratification in Washington.

"That's President Obama's challenge," Turnbull said.

Republican lawmakers who had supported the deal appear to be backing off as a U.S. presidential election looms next year. Many Democrats, including the leading candidate for the Democratic presidential nomination, Hillary Rodham Clinton, oppose the trade pact, which can only be approved or rejected by Congress with no amendments.

Obama acknowledged negotiations were challenging.

"This is not easy to do, the politics of any trade agreement are difficult," he said.

Apart from the U.S. and Australia, Chile, Peru, Mexico, Canada, Japan, New Zealand, Singapore, Malaysia, Brunei and Vietnam have signed on to the accord.

Chinese online commerce mogul Jack Ma had his own suggestion for how to get around the tortuous negotiations process.

His Alibaba e-commerce platform has grown to annual sales worth $500 billion in China, "Almost the same size as Wal-Mart," he said. "If we had negotiations with all the governments and provinces this would go nowhere," Ma told the business leaders.

"Because we never negotiated with them we made this thing happen," he said.