LOS ANGELES — In the lead up to the Summit of the Americas, the Biden administration scrambled to avoid the embarrassment of a boycott by key leaders — only to find its overtures rejected.
American officials spent weeks negotiating with the Mexican government, trying to find a way to entice President Andrés Manuel López Obrador to the meeting in Los Angeles. Vice President Kamala Harris called the leader of Honduras to persuade her to come. Top aides were dispatched to try to convince the leaders of El Salvador and Guatemala.
Nothing worked. The heads of state in all four countries have refused to attend the meeting, a blow to Mr. Biden at a moment when he sought to project unity and common purpose across the Western Hemisphere.
The Salvadoran president, Nayib Bukele, would not even get on the phone with Secretary of State Antony J. Blinken, according to four people familiar with the outreach who were not authorized to speak publicly.
The absences have cast doubt on the relevance of a summit that was meant to demonstrate cooperation among neighbors, but has instead loudly broadcast rifts in a region that is increasingly willing to defy American leadership.
“It shows the deep divisions in the continent,” said Martha Bárcena, the former Mexican ambassador to the United States. The leaders who decided against attending, Ms. Bárcena said, are “challenging U.S. influence, because U.S. influence has been diminishing in the continent.”
The Biden administration has said that much can be achieved without presidents at the table, as foreign ministers sent in their stead are just as capable of signing agreements.
“The U.S. remains the most powerful force in driving hemispheric actions to address core challenges facing the people of the Americas,” Karine Jean-Pierre, the White House press secretary, said on Monday.
Still, while the region’s no-shows are boycotting for different reasons, they all seem to be airing their displeasure with the way the administration wields power.
Mr. López Obrador has telegraphed for weeks that he would not attend unless the administration invited Cuba, Venezuela and Nicaragua. The leftist Honduran president, Xiomara Castro, joined his bandwagon and said she, too, would bow out unless the meeting included those countries.
Leaving them out of the summit, Mr. López Obrador said, “means continuing with the politics of old, of interventionism, of a lack of respect for the nations and their people.”
The leaders of Guatemala and El Salvador appeared more concerned about their own rapport with the United States than the guest list.
Upon taking office, the Biden administration went on the offensive on corruption in both countries, sanctioning high-ranking officials and calling out perceived efforts to weaken democratic institutions by the two Central American governments.
Guatemala’s president, Alejandro Giammattei, said he wasn’t going to the summit a day after Mr. Blinken said that his government’s choice of attorney general was involved in “significant corruption.”
“I sent word that I’m not going,” Mr. Giammattei said, adding: “As long as I am president, this country will be respected and its sovereignty will be respected.”
Mr. Bukele has not made his reasoning public, but people familiar with the Salvadoran president’s thinking say he didn’t see the point of handshakes and photo-ops when the dialogue between the two countries was so fundamentally broken.
