FACTBOX-Guaido vs Maduro: Who is backing Venezuela's two presidents

Jan 29 (Reuters) - The United States imposed sanctions on Venezuela's oil exports on Monday, a major escalation in its support for opposition leader Juan Guaido's bid to oust socialist President Nicolas Maduro.

Like many in the opposition and international community, Guaido says the May 2018 vote in which Maduro won a second term was a sham. He says the presidency is vacant as a result, and on Jan. 23 declared himself president, promising free and fair elections, winning support from the United States and others.

While Maduro faces growing international criticism for undermining democracy, he retains support from key stakeholders both at home and abroad, including Russia and China.

Guaido, who a decade ago participated in protests against late socialist leader Hugo Chavez, is promising a transition to a new government through free and fair elections and an amnesty for military officers who disavow Maduro.

Below is a summary of the support enjoyed by each leader.

MADURO

* The top brass of Venezuela's military has shown no sign of leaving Maduro's side. Defense Minister Vladimir Padrino reaffirmed support for Maduro in a tweet on Jan. 23, saying Venezuela's armed forces disavowed any self-proclaimed president.

* Russia and China, which are major investors in Venezuela's oil industry and significant creditors to the indebted government, have stood by Maduro and criticized U.S. interference. The two blocked a push for the United Nations Security Council to back Guaido.

* The Supreme Court, stacked with Maduro loyalists, has remained solidly behind the socialist leader, ruling last week that all actions taken by the congress - led by Guaido - are null and void.

* State oil company PDVSA, which accounts for most of Venezuela's export earnings, stood by Maduro. "We have no other president" besides Maduro, PDVSA President and Oil Minister Manuel Quevedo, a career military officer, said in a Jan. 23 statement.

* A few left-leaning governments in the region, including Cuba and Bolivia, continue to back Maduro. Mexico, where leftist Andres Manuel Lopez Obrador took office last year, has dropped the previous government's opposition to Maduro and said it will follow a policy of non-intervention.

GUAIDO

* The United States recognized Guaido shortly after he proclaimed himself president on Jan. 23, saying it would use its "economic and diplomatic power" to restore democracy in Venezuela.

* Numerous right-leaning Latin American governments, including Brazil, Colombia and Argentina, also recognized Guaido. Britain, Germany and France all said on Jan. 26 they would recognize Guaido as president if Maduro failed to call fresh elections in eight days.

* Australia, Canada, Israel also recognize the young leader.

* Venezuela's top military envoy to the United States, defense attache Colonel Jose Luis Silva, said he was splitting with Maduro and recognized Guaido as the "only legitimate president."

* There are some signs that support for the opposition is expanding beyond its traditional middle- and upper-class areas. Several protests against Maduro broke out in working-class neighborhoods last week, while many former Chavez and Maduro supporters came out to the massive Jan. 23 opposition march.

* Some low-ranking military officers have expressed discontent with the government. The government on Jan. 21 said it suppressed a military revolt after a group of officers stole weapons, kidnapped officers, and demanded Maduro's removal. (Reporting by Brian Ellsworth and Luc Cohen, Editing by Rosalba O'Brien and Lisa Shumaker)