Nicaragua's sweeping crackdown on opposition poses a test for US President Joe Biden, who has put a top priority on promoting democracy and promised a new, wiser approach in Latin America but has so far deviated little from his predecessor Donald Trump.

The Central American nation has only 6.5 million people but experts say the region will be watching closely whether Biden can impose costs on Nicaraguan President Daniel Ortega.

Authorities loyal to Ortega have rounded up four opposition figures, ruling them out from November presidential elections in which the leftist is expected to seek a fourth consecutive term.

The moves were made with a brazenness rarely seen in recent years in Latin America, where even in Venezuela the opposition leader, Juan Guaido, operates freely.

The Biden administration responded by imposing sanctions on four Nicaraguan officials including the president's daughter. The State Department said it considered Ortega "a dictator" and vowed to exert more pressure.

Nicaraguan President Daniel Ortega, his wife, Vice President Rosario Murillo, and their daughter Camila Ortega  attend the commemoration of the 40th anniversary of the Sandinista Revolution in 2019 in Managua
Nicaraguan President Daniel Ortega, his wife, Vice President Rosario Murillo, and their daughter Camila Ortega attend the commemoration of the 40th anniversary of the Sandinista Revolution in 2019 in Managua AFP / INTI OCON

But Trump also imposed sanctions in Nicaragua as well as crippling measures in Venezuela, where another leftist leader, Nicolas Maduro, has withstood the US-led campaign for more than two years.

Geoff Ramsey of the Washington Office on Latin America, a research group that promotes human rights, said Biden has yet to show how he will "distinguish himself from Trump's bluster."

"On the campaign trail, Biden criticized Trump for prioritizing tough rhetoric over a realistic strategy. Now's the time for the administration to implement a smart strategy that combines targeted pressure with smart engagement in a way that can actually make progress," Ramsey said.

Ivan Briscoe, Latin America program director of the International Crisis Group, said the Trump team erred in Venezuela by making impossible demands on Maduro such as that he completely leave. Few senior officers deserted, with fears for their fate outweighing their discontent.

"If you introduce more sanctions in Nicaragua you need to keep the window open for negotiations which are not solely about Ortega and his family and his allies surrendering and giving up power," Briscoe said.

Nicaraguan presidential candidate Felix Maradiaga gestures as he arrives at the Attorney General's office amid a clampdown on opposition
Nicaraguan presidential candidate Felix Maradiaga gestures as he arrives at the Attorney General's office amid a clampdown on opposition AFP / INTI OCON

"Because if that is the demand, then clearly Ortega is going to resist."

As Nicaragua is the second poorest nation in the Western Hemisphere, Biden is certain to be wary of any measures that could trigger migration -- an early priority for the administration as it faces domestic criticism over the flow of asylum seekers from Guatemala, Honduras and El Salvador.

Outside of migration, the Biden administration has made few significant shifts from Trump on Latin America, toning down rhetoric on Venezuela but still recognizing Guaido as interim president.

US Secretary of State Antony Blinken leaves after listening to President Joe Biden make a speech on the Covid pandemic in St Ives, Cornwall ahead of a Group of Seven summit
US Secretary of State Antony Blinken leaves after listening to President Joe Biden make a speech on the Covid pandemic in St Ives, Cornwall ahead of a Group of Seven summit AFP / Brendan Smialowski

Surprising some observers, Secretary of State Antony Blinken has also shown little immediate interest in reversing the Trump administration's last-minute redesignation of communist Cuba as a state sponsor of terrorism.

Cuban- and increasingly Venezuelan-Americans, many of them fervently opposed to regimes in their home countries, are a major force in politically crucial Florida, where Trump made strong gains among Latinos in the last election.

Martha Lorena Castaneda, a Nicaraguan-American accountant in Washington, warned that the country could turn into a new Cuba or Venezuela if Ortega is re-elected.

"It would be great if the United States stepped in to help, for example by sending observers to prevent corruption in the elections," she said.

The United States has a tortured history with Ortega, with Ronald Reagan's White House clandestinely funding Contra rebels in the 1980s who fought unsuccessfully to topple his leftist Sandinista government.

The United States begrudgingly worked with Ortega after he was elected back to power in 2007 and he recast himself as a friend of business despite his Marxist rhetoric.

Ryan Berg, a senior fellow at the Center for Strategic and International Studies, said it was time to "throw the kitchen sink" and try to break Ortega's bonds with the commercial elite such as by suspending Nicaragua's participation in the CAFTA-DR trade pact.

The Ortegas "are willing to take Nicaragua down with them," Berg said.

The intended audience for US action, he said, is instead "the two-faced, wealthy entrepreneurial class" which would see "that this is serious and our bread and butter is on the line."

Experts said that other leaders known for strong-armed tactics such as El Salvador's Nayib Bukele and Juan Orlando Hernandez in Honduras will be watching.

"If we don't try to find a resolution to the democratic deficits in Nicaragua, it could have a sort of domino effect for other aspiring autocrats around the region," Berg said.

"It would be a big blow for Biden, who is all about promoting democracy, to just let this happen in our own near abroad."