Latin America's Pacific littoral states -- Chile, Colombia and Peru -- will likely be key to cementing U.S. President Barack Obama's Trans Pacific Partnership, analysts say.

But Obama's TPP plans have drawn controversy from within the Democratic Party, intellectual property advocacy groups and other campaigns. Main criticism is aimed at perceived lack of transparency in the ongoing negotiations, most of them behind closed doors. U.S. Sen. Elizabeth Warren, D.-Mass., Thursday called for greater transparency in the talks.

No such challenges confront the TPP effort in Latin America as the U.S. administration moves toward greater engagement with a region seen to have been neglected during long engagement with Afghanistan and Iraq.

Both the president and Vice President Joe Biden have visited Central and South America to build support for the proposed partnership. Americas Quarterly called it "the hottest topic in world trade these days."

Peruvian President Ollanta Humala met with Obama and Biden in Washington, shortly after Chilean President Sebastian Pinera paid the White House a visit aimed at reviving contacts between the two countries.

Chile, Peru and Colombia are backing U.S.-led efforts for greater economic, political and trade integration in a region that stretches from South America's Pacific coast to Southeast Asia, Australian and New Zealand.

Current talks center on including TPP members Australia, Brunei, Canada, Chile, Japan, Malaysia, Mexico, New Zealand, Peru, Singapore and Vietnam. U.S. officials say they hope to conclude the pact before October's Asia Pacific Economic Cooperation summit convenes in Indonesia.

At the talks with Humala, Obama praised Peru as "one of our strongest and most reliable partners in the hemisphere."

Obama cited "a strong commercial and trading relationship" between the countries that includes cooperation on "a wide range of security issues, including our counter-narcotics efforts."

TPP membership as it stands in current talks is expected to rope in major players commanding about 40 percent of the global economy. Japan is the leading East Asia contender but China isn't one and South Korea remains cool to the idea.

In Latin America, too, Brazil is out of the loop while it builds its own trade networks with China, Africa, Europe and the Middle East. Brazil continues to bring Cuba into Latin American limelight and wants U.S. embargo on Havana, the longest in history, to end.

Analysts say the U.S.-led TPP effort also reflects on the future direction of the Pacific Alliance, the 1-year-old bloc that's seen as a counterweight to Mercosur. The alliance includes Chile, Colombia, Costa Rica, Mexico and Peru but also has associates from a wide political spectrum. Like TPP the Pacific Alliance leans toward Asia and in some circumstances is seen to be bypassing Mercosur's multilateral EU links by including France, Portugal and Spain among associate members.

Critics say the U.S. sponsorship of TPP may lead to dismantling of many existing bilateral and multilateral trade agreements but may benefit U.S. corporations. Unless handled correctly, "TPP will not only fail to live up to its potential; it could even sow political and economic discord," Americas Quarterly said.

Obama demonstrated renewed U.S. focus on building Western Hemisphere links with recent visits to Costa Rica and Mexico where he met regional leaders. Biden toured Brazil, Colombia and Trinidad and Tobago.