In a speech to a joint session of Congress, Calderon described efforts to fight organized crime in Mexico, where 23,000 people have been killed in drug violence since he came to power in late 2006 and launched an army offensive.
Washington is also aiding Mexico's battle against drug gangs with a 2007 pledge of $1.4 billion for equipment and police training to help fight the cartels that ship some $40 billion worth of illegal drugs north each year.
The drug violence has become a major political test for Calderon and a growing worry for Washington and foreign investors as violence has spread across the southwest border.
"There is one issue where Mexico needs your cooperation. And that is stopping the flow of assault weapons and other deadly arms across the border," Calderon said to a standing ovation from U.S. lawmakers.
Calderon said the increase in violence in Mexico had coincided with the 2004 lifting of a U.S. assault weapons ban.
The 10-year ban on the sale of assault weapons to civilians expired without being extended by Congress. U.S. Attorney General Eric Holder has said the administration favors reinstituting the ban, though guns rights groups oppose it.
Calderon said he respects Americans' Second Amendment right to bear arms but said many of the guns are getting into the hands of criminals.
SEIZING GUNS
Mexico has seized around 75,000 guns and assault weapons in the last three years, Calderon said. He said more than 80 percent of them came from the United States and noted there were more than 7,000 gun shops along the border.
"I would ask Congress to help us, with respect, and to understand how important it is for us that you enforce current laws to stem the supply of these weapons to criminals and consider reinstating the assault weapons ban," he said.
Though Calderon's request received applause and a standing ovation from mainly Democratic lawmakers, Republicans criticized the Mexican leader for discussing U.S. laws.
"It was inappropriate for President Calderon to lecture Americans on our own state and federal laws," said Senator John Cornyn, a member of the Republican leadership. "Moreover, the Second Amendment is not a subject open for diplomatic negotiation, with Mexico or any other nation."
On immigration -- a common theme during his visit to Washington -- Calderon said his country was trying to improve economic conditions so Mexicans would not feel the need to leave their country in order to succeed.
He said Mexico expected more than 4 percent growth this year, even though data released on Thursday showed the economy shrank quarter-on-quarter in the first quarter of this year.
Millions of people are still crossing the U.S. border illegally to seek work. An estimated 10.8 million illegal immigrants live in the United States, most of them from Mexico and Central America.
Calderon repeated his opposition to a new Arizona law that requires police to check the immigration status of anyone they suspect is in the country illegally.
"We must find together a better way to face and fix this common problem," he said.
And don't worry about guns getting overthe border. We will be deploying the military - nothing wll be moving over the border.
