Story highlights

NEW: Biden meets with Mexico's Calderon and three candidates vying to replace him

NEW: Calderon pushes Biden to do more to stop gun trafficking across the border

NEW: The vice president is expected to be in Honduras on Tuesday

The U.S. has pledged $1.4 billion in assistance for Mexico's drug war

Mexico City CNN  — 

U.S. Vice President Joe Biden on Monday met with Mexican President Felipe Calderon and three candidates vying to replace him.

The meetings were part of Biden’s two-day visit to the region. He plans to be in Honduras on Tuesday.

The two leaders pledged cooperation on a range of issues, according to a statement from Calderon’s office. The Mexican president also pressed Biden on doing more to stop gun trafficking across the border, Calderon’s office said, echoing previous comments from Calderon.

Standing in front of a Mexican government-sponsored, English-language sign in Ciudad Juarez, Mexico, that said “NO MORE WEAPONS,” Calderon said last month that the best thing Americans could do to put an end to the brutal drug violence in Mexico would be to stop sending weapons across the border.

“One of the main factors that allows criminals to strengthen themselves is the unlimited access to high-powered weapons, which are sold freely, and also indiscriminately, in the United States of America,” he said then.

Biden also met Monday with three candidates vying to succeed Calderon in presidential elections this year: Josefina Vazquez Mota, who would be the country’s first female president if she won, Andres Manuel Lopez Obrador, a former mayor of Mexico City who lost the presidency in a disputed vote in 2006, and Enrique Peña Nieto, the former governor of Mexico’s most populous state.

Calderon has been mired in a controversial war on drug cartels in which more than 47,000 people have been killed since he announced a crackdown in December 2006, according to government statistics.

His term is up and by law, he cannot run again.

Violence and the drug war are expected to be key issues when Mexican voters head to polls in July.

Biden’s visit comes a week after U.S. Homeland Security Secretary Janet Napolitano met with Mexico’s interior minister in the nation’s capital and told reporters that the drug war there “is not a failure,” and that it was only a matter of time before the leader of Mexico’s powerful criminal organization falls.

“It took us 10 years to find Osama bin Laden and we found him,” Napolitano said. “And you know what happened there. I’m not suggesting the same thing would happen with (alleged Sinaloa cartel leader Joaquin “El Chapo” Guzman,) but I am suggesting that we are persistent when it comes to wrongdoers and those who do harm in both of our countries.”

The United States admits its drug market plays a role in fueling violence in Mexico, and has pledged $1.4 billion in assistance through the so-called Merida Initiative, which includes programs to help train Mexican military, police and justice officials.

Tourism and trade ties also bind the neighboring nations.

On Tuesday, Biden is scheduled to travel to Honduras to meet with President Porfirio Lobo and other Central American leaders.

Honduras has the world’s highest murder rate, with 82.1 murders per 100,000 inhabitants in 2010, according to the United Nations Office of Drugs and Crime.

Last year, Lobo told CNN en Español that drug use in the United States was a key cause of violence in his country and throughout the region.

“We know what the causes are. We have there in the north a country that consumes drugs, and we are the transit countries. … None of these problems is exclusive to Honduras,” he said.’s Tania Montalvo and CNN’s Rey Rodriguez and Rafael Romo contributed to this report.