MERIDA, Mexico (CNN) -- In his first post-impeachment journey
                  abroad, President Clinton began a short summit Sunday in Mexico to
                  bolster the country's struggle against narcotics and corruption and
                  expand its markets for U.S. products.

                  The president and his wife were greeted when they arrived at sunset by
                  Mexican President Ernesto Zedillo and his wife, Nilda. An honor guard
                  saluted the Clintons, and four children presented flowers.

                  The leaders and their wives later headed to a private dinner.

                  Clinton, traveling outside the United States two days after his acquittal by the
                  Senate, was accompanied by about a half- dozen members of his Cabinet,
                  including retired Gen. Barry McCaffrey, director of the White House Office
                  of National Drug Control Policy, Attorney General Janet Reno, and Export-
                  Import Bank President James Harmon.

                  Clinton brought with him a $4 billion line of credit from the Export-Import
                  Bank to lend to Mexican businesses that buy U.S. goods and services. He
                  planned to announce the aid Monday, an administration official said.

                  In two weeks, the administration must render a formal evaluation of
                  Mexico's cooperation in fighting drug trafficking. Clinton and Zedillo have
                  met about every six months over the past few years, and officials say this
                  meeting is intended to maintain good relations.

                  The presidents are expected to discuss immigration and complete an
                  agreement on safety and environmental protections along their 2,000-mile
                  border.

                  Neighbors to liberalize travel, fight forest fires

                  The administration official, speaking on condition of anonymity, said other
                  agreements the presidents will sign after their Monday summit at Hacienda
                  Temozon include:

                  -- A civil aviation pact to liberalize flights between the United States and
                  Mexico, estimated to be worth hundreds of millions of dollars to the nations'
                  airlines.

                  -- $1.2 million in U.S. funds to the Mexican Nature Conservation Fund, to
                  prevent a repeat of last year's forest and grassland fires South of the border
                  that sent smog into Texas.

                  -- U.S. training and assistance to Mexico's new federal police force, meant
                  to be a fresh start for the country's long-corrupt law enforcement system.

                  -- a campaign in 10 Mexican and 10 U.S. cities in the border area to
                  educate people about tuberculosis.

                  -- a joint effort to coordinate aid to Central American nations hurt by
                  Hurricane Mitch.

                  Mexico could be hit with tough economic sanctions if it receives a failing
                  grade in the drug battle. While the administration says Mexico has a
                  tremendous drug problem, it is believed Clinton will certify Mexico as a
                  cooperative ally in fighting narcotics, as the United States has done in the 12
                  years since the congressionally mandated review process began.

                  Even before Clinton's trip, the administration appeared to be laying
                  groundwork for a positive report while acknowledging that cocaine seizures
                  by the Mexican police have dropped.

                  "We think we've made a lot of progress over the last year," said James
                  Dobbins, the National Security Council's senior director for InterAmerican
                  Affairs.

                  Congress' skepticism could fuel Mexican nationalism

                  Yet White House certification could be overturned by a two- thirds vote in
                  Congress, where skepticism runs deep about the Zedillo government's
                  performance.

                  Such a congressional action could trigger a nationalist backlash in Mexico,
                  where the certification process is widely disliked.

                  The process "is frankly against the spirit of collaboration that should exist
                  between our two countries, our governments and our peoples," Mexican
                  Foreign Minister Rosario Green said ahead of the Clinton visit.

                  Relations between the countries have been further strained by the
                  Casablanca sting operation in which the U.S. Justice Department
                  investigated Mexican banks involved in money laundering without informing
                  their Mexican counterparts.

                  In an apparent reference to Casablanca, Mexican legal officials are
                  considering a measure to punish police agents from other countries who act
                  without authorization on Mexican soil.

                  Mexico blames the United States for much of its drug problem, because
                  U.S. citizens are the world's biggest buyers of illicit narcotics. Yet in hopes
                  of winning certification, Mexico announced a $400 million "total war"
                  February 4 that calls for buying aircraft, ships, radar, X-ray equipment and
                  other items.

                  Mexico is a major transit point for cocaine shipments from South America to
                  the United States. It also is a major producer of marijuana and a significant
                  producer of heroin.

                  With friction over drugs, the administration sought to highlight progress on
                  another front: booming economic trade between the United States and
                  Mexico in the five years since the North American Free Trade Agreement.

                  Mexico has emerged as the second-largest foreign market for U.S. exports,
                  after Canada. It eclipses even Japan, a U.S. official noted.

                  U.S. exports to Mexico total $79 billion a year, more than twice the
                  pre-NAFTA figure. Mexico accounts for close to 20 percent of the total of
                  U.S. export growth in the past five years.

                     CNN White House Correspondent John King,, The Associated Press and Reuters
                                      contributed to this report.