Founded in 1991, Mercosur is a sub-regional economic bloc that includes Argentina, Brazil, Paraguay, Uruguay and Venezuela.
Uruguay is currently seeking to transfer the Mercosur presidency for this half of the year to Venezuela. However, there have been concerns over growing discord in Venezuela amid a political standoff between Venezuela's President Nicolas Maduro and the opposition-dominated parliament.
Both Paraguay and Brazil have raised the possibility of blocking Venezuela's chairmanship due to what is being claimed to be a breakdown of democratic order in Venezuela.
Argentina has not expressed any opposition to Venezuela assuming its presidency in July.