Three US senators from President Obama's Democratic Party have said that there could be enough support from the majority Republicans in Congress to lift a trade embargo on Cuba, as they concluded a four-day visit to Havana.

Democratic senators Claire McCaskill, Mark Warner and Amy Klobuchar issued the statement on Tuesday, as Obama's Democratic allies in Congress, led by former House Speaker Nancy Pelosi, headed to the communist island nation in a bid to further improve relations between the countries.

The US and Cuba agreed on December 17 to restore diplomatic relations after more than five decades of hostility.

Obama has already started to lift barriers to trade and travel, but only an act of Congress can end the decades-long embargo.

Both the Senate and House of Representatives are controlled by the Republican Party. 

Republican and Democratic senators have introduced two separate bills to lift travel restrictions on Americans going to Cuba and to repeal the 53-year-old embargo.

Senator Klobuchar is the lead sponsor of the embargo bill and a co-sponsor of the travel bill.

The two bills face serious opposition in the Senate and House of Representatives.

But some Republican legislators have expressed support, such as Senator Jeff Flake, lead sponsor of the travel bill.

Senator McCaskill said largely Republican agricultural interests in the US Midwest region supported lifting the embargo as "they really want to sell rice down here".

US business interests such as the US Chamber of Commerce have also long opposed the embargo as a violation of the principle that government should not impede free enterprise.

Pelosi visit

Pelosi and eight other Democrats plan to meet with the Cuban government, church and local officials, and with Americans representing the US government there.

"This delegation travels to Cuba in friendship and to build upon the announcement of US normalisation of relations and other initiatives announced by President Obama," Pelosi said on Tuesday.

"This delegation will work to advance the US-Cuba relationship and build on the work done by many in the Congress over the years, especially with respect to agriculture and trade."

Source: Agencies