Canada and Mexico want to join talks to forge a free trade area in the Asia-Pacific region, giving a significant boost to the U.S.-led initiative to foster economic growth by tearing down trade barriers.
Japan, the world's third-largest economy, said earlier it would like to join.
Canadian Prime Minister Stephen Harper said on Sunday he was encouraged to take part by U.S. President Barack Obama.
We looked at the outline of the criteria set by the partnership and they are all criteria that Canada can easily meet. So it is something we're interested in moving forward on, Harper said at the Asia-Pacific Economic Cooperation summit of 21 nations in Hawaii.
Mexico's economy minister told Reuters his government would also ask to join the talks.
Mexico is interested in beginning consultations to join the Trans-Pacific Partnership, Bruno Ferrari said, adding the agreement potentially offered his country an opportunity to boost growth.
The United States welcomed the interest of its two neighbors, with all of them already partners in the NAFTA trade pact.
The proposed TPP pact now includes nine countries -- the United States, Australia, New Zealand, Singapore, Malaysia, Brunei, Chile and Peru -- that have committed to what they call a high-standard trade agreement.
They must approve new applicants. The TPP goal is to complete a detailed framework in 2012 and adding new members could slow the timetable.
Japan strengthened the significance of the talks on Friday when it expressed its interest in joining the pact, which analysts see as important to ensuring the United States maintains a strong economic presence in the region as China continues to rise.
With Japan included, the proposed economic pact would be about 40 percent larger than the 27-nation European Union.
U.S. Trade Representative Ron Kirk said the administration was looking forward to talks with Canada and Mexico, as well as U.S. lawmakers and others, and to discussing the TPP's high standards for liberalizing trade and specific issues of concern to the United States.
Along with Japan's similar announcement this week, the desire of these North American nations to consult with TPP partners demonstrates the broadening momentum and dynamism of this ambitious effort towards economic integration across the Pacific, Kirk said in a statement.
The United States and Canada have been free trade partners since the late 1980s, first under a bilateral agreement and then the North American Free Trade Agreement that brought in Mexico in 1994.
But negotiators are addressing many issues in the TPP talks that have arisen since NAFTA went into force. Those include the role of state-owned enterprises in international trade, government innovation policies and cross-border data flows.
(Reporting by Rachelle Younglai and Doug Palmer; Editing by John O'Callaghan)