Venezuela opposition candidate pressured by allies to choose a substitute, sources say

By Vivian Sequera and Mayela Armas

CARACAS (Reuters) - Venezuela opposition leader Maria Corina Machado is facing increasing pressure from her allies to choose a substitute to potentially run in her place in the July presidential election, five sources with knowledge of the matter said.

Machado, a 56-year-old industrial engineer, won the opposition's nominating contest in October by a landslide, but Venezuela's top court has since upheld a ban on her candidacy that was imposed over her support of U.S. sanctions, among other things.

Machado has so far refused to consider a substitute, saying her ban is an effort by President Nicolas Maduro to protect himself from a viable opposition challenger.

But the clock is ticking on a decision - candidates have between March 21 and March 25 to register formally, though substitutes can be admitted until April 20. The election itself has been set for July 28.

Leaders of opposition parties this week asked Machado to define a strategy, and though they have expressed their support for her candidacy, they want her to decide on an alternative candidate, the opposition sources said.

"There are pressures on her to not leave (the substitution) too late," one of the sources said.

Machado did not respond to a request for comment. A representative for her party told journalists this week it was weighing different scenarios, without giving further details.

"One day at a time," she said in the central state of Carabobo on Wednesday, when asked about what would happen were her registration rejected.

"I think Maduro needs to think really hard about how he will look to the country," she added.

The U.S. has insisted the Maduro government lift the ban on Machado and said recently he has not complied with an election guarantee deal signed last year.

"The United States is key in this process," another source said.

Some of the sources said Washington could urge Machado to make a decision on a substitute, though State Department official Brian Nichols said last week the U.S. would take its cues from the opposition.

"The United States will continue to support the will and the right of Venezuelans and Venezuelan political parties to select their presidential candidates," a White House National Security Council spokesperson said when asked about pressure on Machado and whether or not the U.S. wants her to step aside.

The State Department did not immediately respond to a request for comment.

The U.S. has already said a relaxation in oil sanctions will expire in mid-April unless Machado can run.

Before the October primary several candidates urged the creation of a substitution plan, but no mechanism was ever agreed. Any substitute could also face a ban.

(Reporting by Vivian Sequera and Mayela Armas in Caracas, additional reporting by Matt Spetalnick in Washington and Tibisay Romero and Johnny Carvajal in Valencia; Writing by Julia Symmes Cobb; Editing by Rosalba O'Brien)