Secretary of State John F. Kerry has canceled a tentative trip to Cuba two weeks before President Obama visits the communist-ruled nation as diplomats haggle over which Cuban dissidents the president will be allowed to meet.
The back and forth over human rights is another sign of how prickly U.S.-Cuba relations remain despite the restoration of diplomatic ties, and the easing of many travel and trade restrictions, over the last year.
It also highlights a potential problem for Obama's planned overnight visit on March 21, the first by a sitting president in nearly 90 years, to the former Cold War adversary.
Despite the U.S. push toward normalization of relations, the government in Havana has done little to ease its limits on free expression or to improve treatment of human rights activists and political dissidents.
President Raul Castro has supported opening the Cuban economy to incorporate free-market elements, including private enterprise and private ownership of homes and cars, for the first time since the 1959 revolution that brought the communists to power.
But he has insisted that the political system and the "socialist nature of the revolution" will not change. His Foreign Ministry official for U.S. affairs, Josefina Vidal, has described the U.S. focus on human rights as hypocritical.
Despite that resistance, Obama, in his announcement last month of his two-day trip, said he aims to engage with the Cuban people. Previously, he had said he would not go unless Cuba allowed significant progress on human rights.
"We determine who we meet with in different countries," Ben Rhodes, Obama's deputy national security advisor, said Feb. 18. "And we've certainly indicated to the Cubans that this is something the president will be doing on this trip, as he does on other trips."
Kerry, who flew to Havana in August to reopen the U.S. Embassy, had hoped to return by week to lay the groundwork for Obama's visit and to "have a human rights dialogue, specfically," he told the Senate Foreign Relations Committee on Feb. 24.
But that trip was scrubbed, officials said Thursday, when arrangements could not be finalized.
Kerry "is still interested in visiting in the near future, and we are working with our Cuban counterparts and our embassy to determine the best time frame," said John Kirby, the State Department spokesman.
Other officials said the new U.S. Embassy, which remains a bare-bones operation, was overwhelmed trying to arrange back-to-back visits by Kerry and Obama.
When U.S. diplomats began negotiations for Obama's visit, they said any attempt to block him from meeting dissidents would be a deal breaker, according to a White House official who spoke on condition of anonymity because of diplomatic sensitivities.
But political dissidents in Cuba are a varied bunch.
Some are so bitterly anti-Castro, they disapprove of Obama's rapprochement and might refuse an invitation. Others, known worldwide, are despised by the Cuban government.
Cuba now holds several dozen political prisoners in its jails, according to Cuban activists, down from several hundred a few years ago. But the government still harasses dissidents by detaining them for brief periods.
In January, 1,414 political dissidents were detained, the second highest number in years, according to Elizardo Sanchez, head of the opposition Cuban Commission for Human Rights and National Reconciliation. He said 56 of the detainees were beaten.
The cost of repression "is incalculable," he said in a recent report, noting the stigma and lost employment resulting from even brief arrests.
Perhaps of most concern to the Obama administration is the rearrest of five people who were released as part of the surprise announcement Dec. 17, 2014, that Cuba and the U.S. were restoring diplomatic ties after more than half a century.
"It is hard to speak of progress when they make these rearrests," a senior State Department official said, speaking on condition of anonymity to provide details of private negotiations. "We have to keep pushing them on this."
Republican presidential candidates and other critics, including some Democrats, have denounced the White House decision to visit Cuba, saying it rewards a still-repressive, undeserving regime.
Obama's supporters view his trip as a critical step toward normalization and bringing Cuba's economy into the 21st century after five decades of enforced isolation.
"Do the Cuban people deserve this visit? The answer is overwhelmingly yes," said James Williams, president of Engage Cuba, an umbrella organization of groups that seek the lifting of all trade and travel restrictions.
Christopher Sabatini, adjunct professor at Columbia University's School of International and Public Affairs, suggested that Obama find ways to make direct contact with ordinary Cubans, much as Pope Francis did with unscheduled stops during his recent visit to the country.
"The mere fact of a president going to a country isn't a Good Housekeeping seal of approval of a government's behavior," Sabatini wrote on the website he edits, LatinAmericaGoesGlobal.org.
But if done right, he added, it can "send a strong signal of solidarity with local citizens, rather than an endorsement" of the government.