Mexican President Felipe Calderon meeting Obama
Mexican President Felipe Calderon and US President Barack Obama are meeting at the White House, amid heightened tensions between their two nations.
Mr Calderon is also scheduled to meet House Speaker John Boehner during his trip to Washington.
The talks are expected to focus on immigration, economic issues and anti-crime co-operation.
The visit comes weeks after the killing of a US agent in Mexico and leaked US criticism of Mexico's war on drugs.
The Mexican president's first meeting was with US business leaders on Wednesday evening, with discussions focussing on opportunities for foreign investment in Mexico.
Mr Obama is committed to the "strong partnership that the United States has with Mexico. That is the reason for the meeting," said White House spokesman Jay Carney.
Mr Calderon is expected to speak to Mr Boehner before leaving Washington about the $1.3bn (£799m) the US is spending as part of the Merida Agreement, which provides materials and training to help Mexico tackle drug-trafficking.
Commentators say that the costs of Mexico's drug war, diplomatic cable leaks, anti-immigration initiatives in the US and the influx of US arms into Mexico are all working to degrade a relationship between the two countries that had until recently seen improvement in the past several years.
The BBC's Steve Kingstone, in Washington, says that the backdrop to this visit could not be grimmer.Zapata killing
The meeting at the White House comes roughly two weeks after US Immigration and Customs Enforcement agent Jaime Zapata was shot dead in northern Mexico, reportedly with a weapon that came from the US.
On Sunday, the Mexican military arrested the suspected local head of the Los Zetas drugs gang in the northern state of Coahuila.
Another alleged member of the gang has been arrested on suspicion of carrying out the killing.
US and Mexican officials have repeatedly said that Mr Calderon's trip was scheduled before Zapata's death.
Officials in Washington have said the Obama administration has been working with the Mexican government to better protect US personnel working in Mexico.
Adding to recent tensions between the two countries was the release of leaked cables written by US embassy personnel, who described Mexico's armed as inefficient, corrupt and reliant on the US for leads and operations.
Mr Calderon was said to have reacted furiously to the release and objected to cables that talked about a lack of co-ordination among Mexican agencies.
Mexican officials have also reportedly been angered at the tough measures to stop illegal immigration in several US states, like Arizona and Texas.