President Bush and his Mexican counterpart, Vicente Fox, are meeting in the Mexican resort city of Cancun on Thursday for talks covering proposed new immigration laws in the United States.
Mr. Bush is also set to hold talks with new Canadian Prime Minister Stephen Harper on border security, as well as a softwood lumber dispute between their two countries.
The talks come as the U.S. Senate debates the contentious issue of immigration. Republicans are split on whether to back President Bush's call for sweeping reforms, including creation of a temporary worker program.
Hoping to influence the decision, hundreds of thousands of people marched through several U.S. cities this week to demand humane treatment for undocumented migrants.
President Fox is expected to urge President Bush to legalize the status of the millions of undocumented Mexican migrants living in the United States. He is also expected to urge Canada to expand its guest worker program for Mexicans.
Mr. Bush is also hoping to resolve the timber trade dispute with Canada, which broke off talks last year in protest over a U.S. decision to continue to collect tariffs on Canadian softwood lumber imports. Officials with the North American Free Trade Agreement have ruled the tariffs are illegal, but the Bush administration says its position is supported by the World Trade Organization.
The U.S. has collected four-and-a-half billion dollars in duties on the Canadian lumber imports since 2002.