SAN JOSE, COSTA RICA – In search of trustworthy partners, the Biden administration dispatched its top diplomat to Costa Rica on Tuesday to take Central American officials to task on corruption in their countries and to examine how they can more efficiently block migration to the U.S.

He could face a tough crowd.

U.S. relations with the governments of El Salvador, Honduras and Guatemala, in particular, are badly strained, complicating President Joe Biden's plan to use $4 billion over the next four years to boost democratic reforms and improve the economies in those three so-called Northern Triangle nations — the source of most migrants attempting to enter the U.S. illegally.

Secretary of State Antony Blinken plans on "a very frank and honest" exchange of views with his Central American counterparts, said Julie Chung, assistant acting secretary of state for the Western Hemisphere.

Good governance and rule of law "are some of the issues that are the drivers of why people leave their homes in the first place," she said. "They don't have confidence in their governments."

Blinken is attending an annual meeting of the foreign ministers of the eight-member Central American Integration System, an economic and political association of all Central American countries plus the Dominican Republic.

Administration officials say they have already made clear to the Central American presidents that very little of the $4 billion will go to the central governments and instead will be channeled through nongovernmental organizations and other private entities.

To underscore that warning, the U.S. Agency for International Development last week announced that it was diverting all aid it gives El Salvador from the government to "civil society" groups that monitor human rights and fight corruption.

The move came after Salvadoran President Nayib Bukele fired the country's attorney general and Supreme Court magistrates and then ignored entreaties from Washington and elsewhere to reconsider what was widely seen as an illegal power grab.

Relations with Bukele have been especially tense. He refused in recent months to receive Biden's visiting envoy in charge of the Northern Triangle, Ricardo Zúñiga; he eventually relented, then appeared to be stunned by the scolding he received, officials said.

The Biden administration is concerned about what it sees as similar erosions of democracy in Guatemala, where President Alejandro Giammattei has sought to undercut the courts, and in Honduras, which has an especially difficult problem. Its president, the staunch Trump ally Juan Orlando Hernandez, is under federal investigation in the U.S. on drug-trafficking allegations. Administration officials have said privately they will shun him.

Dealings with Nicaragua, which is also expected to be present at the summit but may send a lower-level delegate, could become a point of contention. No U.S. administration has had a good relationship with Managua for years.