CANCUN, Mexico (AP) – The leaders of the United States, Mexico and Canada are converging in this bikini-and-beer mecca for a second annual show of North American unity.

Despite the emphasis on cross-border comity and cooperation, however, the neighbors come together with no resolution of nagging issues that for years have strained U.S. relations with its two largest trading partners.

President Bush arrived in Cancun on Wednesday evening to an understated welcome from just a few local officials gathered at the bottom of Air Force One’s stairs for the two-day summit with Mexican President Vicente Fox and Canadian Prime Minister Stephen Harper.

With separate bilateral meetings set for Thursday, followed by joint sessions with all three leaders on Friday, Bush promptly turned in for the night in his luxury hotel along the Caribbean resort’s sugar-white beach while thousands of winter-weary college students prowled Cancun’s bars nearby.

With illegal immigration, sticky trade disputes, terrorism fears and other weighty matters on the agenda, the president made clear that his approximately 40-hour stay in Cancun would be no spring break. “No Speedo suit here _ thankfully,” he joked earlier Wednesday to a Washington audience.

Thursday morning, Bush was beginning his Mexico visit _ the fifth of his presidency _ with a rare sightseeing foray. Eschewing the all-business routine of most foreign of his trips, the president carved out half a day to fly by helicopter to the famed Mayan ruins at Chichen Itza.

Later, Bush was sitting down one after the other with Fox and Harper, and then was attending a lavish leaders dinner put on by his Mexican hosts. The president’s wife, Laura, did not join him for this trip.

The official focus of the trilateral summit is a three-way pact designed to make borders more secure without hampering business and traffic. Signed a year ago near Bush’s Texas ranch by Bush, Fox and Harper’s predecessor, Paul Martin, the Security and Prosperity Partnership aims to better protect North America from outside attack and ensure its global competitiveness with China and other trade powerhouses.

But Fox and Harper come to Cancun with much more on their minds. Both have powerful constituencies at home pressing for progress on problems related to the enormous flow of goods and people between their countries and the United States.

Mexico’s top priority with its northern neighbor is a migration accord that would address the status of the estimated 6 million illegal immigrants from Mexico now living in the United States. For Canada, issue No. 1 as it looks south is a messy trade dispute over softwood lumber.

Bush extended an olive branch in both directions before the trip. He told foreign reporters “don’t underestimate” his ability to wring from Congress a guest-worker program that would address some of Mexico’s concerns, and said he would “like to get the issue solved” on Canadian lumber tariffs.

Sharing Cancun with the media, official entourages from three nations and hundreds of anticipated demonstrators was a much-smaller-than-usual contingent of spring-breakers since the resort hasn’t completely recovered from the beating delivered five months ago by Hurricane Wilma. Police readied the town by erecting fences to keep protesters and others far from the leaders.

Bush departed Washington for his meetings with Fox as an emotional election-year dustup over immigration _ what he called the “topic du jour” _ continued to rage in the U.S. capital.

The issue has sent hundreds of thousands to protest in streets across America and split the president’s Republican Party as midterm congressional elections approach.

The Senate was debating a measure that would strengthen border security, but also would legalize some undocumented workers, establish temporary guest-worker programs and permit illegal immigrants currently in the country to apply for citizenship without first returning home.

The business community and a minority of Republicans in Congress have supported such moves, and the approach tracks more closely with what Bush has advocated than competing House legislation that focuses on an illegal immigration crackdown.

Fox wants some form of legal status for all illegal Mexicans but sees a guest worker program as a good step. If one is approved before July elections to succeed him _ Fox is term-limited from running again _ analysts believe it could boost the chances of the candidate from his party.

As for Harper, the newly elected Conservative leader has made it a priority to restore Ottawa’s relationship with Washington _ strained over Iraq, missile defense and a series of trade issues.

Topping Harper’s agenda is the stalemate over U.S. tariffs on Canadian softwood lumber imports. Another issue is Canada’s displeasure at a U.S. plan to require passports or other secure identification at every point of entry to the United States.