Vice President Joe Biden is in Mexico today to meet with all three candidates in that country's presidential election, but the White House isn't taking any sides.

Biden left Washington Sunday night and is in Mexico today, meeting with Mexican President Felipe Calderón. But Calderon is barred from running for reelection in July, so Biden is taking the opportunity to visit with his possible successors. On Tuesday, Biden will travel to Honduras to meet with President Pepe Lobo.

"This trip is the latest chapter in the administration's sustained, high-level engagement with our partners in the Americas. The economic security, familial, historic and cultural ties we share with the Americas and particularly with Mexico and Central America, are among the most consequential we have as a country," said Biden's National Tony Blinken on a conference call with reporters.

"The ongoing challenge posed by the drug cartels and transnational criminal organizations is one critical shared responsibility. We strongly support Mexico's efforts in dealing with this challenge, and the United States and Mexico are collaborating as never before."

Biden will also meet with presidential candidates Andrés Manuel López Obrador, Enrique Peña Nieto, and Josefina Vázquez Mota, in alphabetical order, as to not appear to be playing favorites.

"He'll underscore to each that the United States will continuing working with President Calderon and his administration until the final day that they're in office, and that we look very much forward to working with whomever the Mexican people elect as their next president," Blinken said.

Blinken wouldn't comment on the statements by Sen. John McCain (R-AZ) questioning whether one of the Mexican presidential candidates would continue Calderon's commitment to the increased tempo and aggressiveness of the campaign against the Mexican drug cartels.

In a February hearing with Director of National Intelligence James Clapper, McCain asked Clapper whether the next Mexican president would keep up the campaign that Calderon began in Dec. 2006. Clapper said yes.

"Well, I might suggest you focus on that question a little more closely, Mr. Director, because I don't believe that's the case, at least with respect to one of the candidates," McCain said, not identifying which candidate he was talking about.

Both Obrador and Nieto have made statements indicating they might pull the Mexican military back from the fight if elected.

On Tuesday, after meeting with Lobo, Biden will attend a working lunch to prepare for the upcoming Summit of the Americas. At that lunch will be several regional leaders, including the presidents of Honduras, Guatemala, El Salvador, Costa Rica, and Panama.

At that meeting, drug policy is set to be discussed as well, including the increasingly popular proposal in Central America of decriminalizing drug use and altering the current policy regarding fighting the cartels. But the Obama administration is not on board with what would be seen in the United States as a radical departure from longstanding U.S. drug policy.

"The Obama administration has been quite clear in our opposition to decriminalization or legalization of illicit drugs," said NSC Senior Director for Western Hemisphere Affairs Dan Restrepo. "At the same time, we've also been very open -- the president has said it on numerous occasions, in meetings with leaders and publicly -- of our willingness, our interest, in engaging in a robust dialogue with our partners to determine how we can be most effective in confronting the transnational criminal organizations, and, as in the case in Central America, the gangs that are adversely affecting people's daily lives and daily routines."