Secretary of State Marco Rubio said on Monday that Venezuela's electoral infrastructure wasn't designed to carry out valid elections and must be replaced before any can be held. 

Rubio's statements follow the return of opposition leader Maria Corina Machado, who had been in exile since December. 

A senior State Department official said that the U.S. believes talks currently underway between the interim government in Caracas and opposition politicians are expected to produce a new supreme judicial tribunal ​by the end of this year and a new electoral council shortly after, Reuters reported. 

Rubio said that the U.S. is "making real progress" toward establishing a legitimate electoral infrastructure in Venezuela. 

"But if anybody tries to derail that process, they're doing a ​great harm to Venezuela," Rubio warned. 

Rubio didn't provide a target date for elections. Machado has said elections should be held by mid-2027, a timeframe President Donald Trump said Venezuela isn't likely to meet.