A man works on a scaffold preparing the venue for the seventh Summit of the Americas in Panama City, Panama. (Alejandro Bolivar/EPA)

Cuba ends more than five decades of official isolation in the Western Hemisphere this week when President Raúl Castro attends a regional summit with up to 35 heads of state and government, including President Obama.

The White House said there will be “many opportunities” for conversations between the two leaders at the two-day Summit of the Americas that begins Friday in Panama, but noted that no formal bilateral meeting had yet been planned.

While administration officials said it was unlikely that the United States and Cuba would complete negotiations aimed at re­establishing diplomatic relations before the summit, there were strong indications that one of the main roadblocks in the talks was about to be removed.

The State Department is on the verge of completing a review of Cuba’s 33-year presence on the U.S. list of state sponsors of terrorism, ordered by Obama when he and Castro announced the ­Cuba-U.S. rapprochement Dec. 17, officials said. Although three high-level negotiating sessions have been held since then, Havana has balked at moving forward on reopening embassies until it is taken off the list.

“As soon as I get a recommendation” from the State Department, “I’ll be in a position to act on it,” Obama told NPR in an interview broadcast Tuesday.

For Castro, attendance at the summit is a symbolic reentry into the hemispheric infrastructure that avoids the question of Cuban membership in the Organization of American States, which Havana still considers an instrument of U.S. foreign policy. Although the OAS, which expelled Cuba in 1962, has invited the country to rejoin, Castro has said he would “never” do so.

Obama leaves Wednesday for a four-day trip to the region, traveling first to Jamaica to meet with a 15-nation grouping of Caribbean nations and arriving Thursday evening in Panama.

The hemispheric summit, held every three years, is the third of Obama’s presidency and the first not overshadowed by Latin American opposition to U.S. insistence that Cuba be excluded. Previous summits, held in 2009 in Trinidad and Tobago and in 2012 in Colombia, failed to issue joint declarations because of disagreements over Cuba.

“We, frankly, having gone through two previous summits, did not think it was constructive for the United States to continue to try to isolate Cuba,” said deputy national security adviser Benjamin Rhodes. “It only pointed to the failure of U.S. policy.”

Each time the United States took part in the Summit of the Americas, the question at issue was not about “improving democratic values,” Rhodes said, but “why Cuba wasn’t at the summit.”

Beleaguered by ongoing crises in the Middle East and Ukraine as well as polarized politics at home, Obama is likely to find the visit a welcome respite.

This time, “there is no question that Obama goes from a position of strength, with the wind at his back,” said Mack McLarty, an architect of the summit process, which began under the Clinton administration in 1994. Resolution of the Cuba situation “takes away a very contentious, complicated issue” of previous gatherings, McLarty said.

Obama’s current popularity in much of the hemisphere is due to more than the Cuba opening, regional experts said. There is broad recognition that the administration has “gone as far as they could through executive action” in changing U.S. immigration policy, said Harold Trinkunas, Latin America director at the Brookings Institution. Even though congressional Republicans have rejected administration initiatives, “people recognize the administration’s goodwill effort,” he said.

U.S. counternarcotics policy, another long-contentious issue, has also undergone significant changes. The United States has largely dropped demands for what Latin American countries considered odious certification of their compliance with U.S. drug-enforcement policies to be eligible for certain forms of American aid.

“Obama has a strong record to bring to Panama,” said Jorge I. Dominguez, vice provost for international affairs at Harvard University and author of numerous books on hemispheric affairs. The U.S. economic recovery, he said, has also put Obama in a strong position with regard to Latin America, where a period of sustained economic boom has long since ended.

Obama’s 2016 budget request included $1 billion for Central American economic, governance and security strengthening, keyed to addressing conditions that have led to unprecedented flows of illegal immigrants from that region.

Obama also plans a visit to the Panama Canal, where an expansion due to be completed next year will double the size of tankers and other cargo vessels that can pass through the waterway, to the advantage of ports along the U.S. East Coast.

If there is a fly in the ointment for the United States and the summit planners — and it could be a big one — it is Venezuela. In the weeks since the White House placed new sanctions on seven Venezuelan officials it accused of human rights abuses, President Nicolás Maduro has spoken of almost nothing else, attempting to shift attention away from his government’s economic troubles.

In the Jamaica meeting with members of the Caribbean Community, known as Caricom, Obama will continue efforts begun early this year at an energy security summit hosted by Vice President Biden to nudge Caribbean nations away from supporting Venezuela at regional institutions such as the OAS. Venezuela provides cut-rate oil to at least a dozen Caricom members — as it does for Cuba — and the administration is trying to persuade those countries to diversify their energy sources and turn their allegiances northward.

If Maduro seizes the spotlight in Panama and twists his domestic struggles into a clash with the United States, “the summit could get hung up on the region’s dislike of sanctions . . . which Maduro and his allies have used as proof that the United States has continued in its trajectory of paternalistic behavior” in the region, said Carl Meacham, director of the Americas Program at the Center for Strategic and International Studies.

Although they are in the minority, Maduro also retains friends, including Bolivia’s President Evo Morales and Ecuador’s President Rafael Correa. Even those with little sympathy for Maduro are uncomfortable over the sanctions. Colombian President Juan Manuel Santos, a key U.S. ally, called them “counterproductive.”

But most attention will be on Cuba and the extent to which Castro feels it necessary to support Maduro. With the future of cash-strapped Venezuela’s largesse increasingly in doubt, Cuba is especially keen to attract foreign capital. Castro has an unparalleled opportunity to make the case that his country is modernizing, opening to foreign investment and poised for growth.

Miroff reported from Havana.

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