A group of senators have introduced a bill to slow down the reopening of Cuba as the federal government inches closer to reestablishing ties. The senators, among them two presidential hopefuls, aim to restrict the flow of U.S. money into Cuba as restrictions become more lax.

Republican Sen. Marco Rubio introduced the "Cuban Military Transparency Act" to the U.S. Senate on June 3 to "prohibit financial transactions with the Cuban military" and establish other protocols. The U.S. government, however, has been in negotiations since December, when it announced it would begin reestablishing ties with the Communist state.

Six Republican senators and one Democrat, Sen. Robert Menendez of New Jersey, back Sen. Rubio's bill. Sen. Ted Cruz is one of the Republican backers and is also competing with Sen. Rubio for his party's presidential nomination. These three senators are all of Cuban descent and have vocally opposed the Obama administration's efforts to resume relations with the island nation.

The bill outlines that much of the businesses in Cuba are owned by Gaesa (Grupo de Administracion Empresarial S.A), under the purview of the Cuba military and the Castro family. Among the industries Grupo Gaesa operates is tourism, including hotels, restaurants and car rentals. Subsidiaries of Gaesa also own different parts of Cuban industry.

The bill seeks to restrict the flow of U.S. money to these businesses as the money fills the Cuban military's coffers by banning transactions with the Cuban military, its members, and any entities it may own. This would open U.S. citizens wishing to travel to Cuba to potential penalties.

The only exceptions include the sale of medicine, medical equipment and "agricultural commodities" as well as remittances to relatives and any expenses used "in furtherance of democracy-building efforts for Cuba described in section 109 of the Cuban Liberty and Democratic Solidarity (LIBERTAD) Act of 1996."

To highlight the importance of denying the Cuban military this income, the bill mentions downing of American plans by Cuban fighter jets on Feb. 24, 1996 as well as the island's involvement in the shipping of weapons and fuel to North Korea, a breach of U.N. sanctions on North Korea.

"It is not in the interest of the United States or the people of Cuba for the U.S. to become a financier of the Castro regime's brutality," Sen. Rubio said in a statement.

"The Cuban Military Transparency Act would prevent U.S. dollars from getting into the hands of the Cuban military and would demand accountability from the Obama Administration regarding fugitives of American justice in Cuba, the return of stolen and uncompensated property and the role of the Ministry of the Revolutionary Armed Forces and the Ministry of the Interior in Cuba."

The bill demands accountability through annual reports on the role the Cuban military and Cuban interior ministry play in the economy. The report would identify what businesses the Cuban military owns, and what other businesses and countries it deals with.

Another report would investigate the American properties the Cuban government took during the revolution.

Those opposed to the Obama administration's negotiations have expressed concern over the Cuban government's continued human rights abuses and their intransigence on press and political freedom.

"With the Cuban government and armed forces controlling more than 80 percent of the country's economy, current efforts to expand commerce and travel to Cuba only enrich the Castros' military monopolies," explained Sen. Menendez in a statement.

"The Cuban military uses these funds to violate human rights and jail its opponents. This common sense legislation aims to ensure the American public is not a blind accomplice to the Castro regime's repression."

Assistant Secretary of State Roberta Jacobson, head of the department's Bureau of Western Hemisphere Affairs, has been in negotiations with the Cuban government, but has made little meaningful progress, having failed to reach an agreement on the movement of U.S. embassy personnel and other issues.

However, the bill introduced by the senators threatens to hinder the delicate relationship and may deter Americans from traveling abroad after President Obama lightened travel restrictions.

Yet, many Americans favor negotiating with Cuba. An MSNBC/Telemundo/Marist poll found 59 percent of Americans favored reestablishing ties. A Washington Post poll done with Univision and Fusion found 73 percent of Cubans have a positive outlook of the negotiations.

The State Department has yet to answer a request for comment on the new bill.