EU leaders suspended a summit on Monday after failing to reach a deal on how to fill the bloc's top jobs.
Their inability to reach a solution despite negotiations running for nearly 20 hours in Brussels reflected the fragmented state of the bloc's parliament.
Asked what the main sticking point in negotiations was, an EU official said: "The whole package."
French President Emmanuel Macron, who left the venue shortly after the talks were abruptly called off until Tuesday morning, labelled the breakdown a "failure".

Kuwait launches probe into espionage, state security cases
Trump, Iran threaten to escalate conflict with attacks on energy and water facilities
Israeli airstrikes kill four in Gaza, Palestinian officials say
Iran says Hormuz open to all but ‘enemy-linked’ ships
GCC renews condemnation of ongoing Iranian attacks
Seven killed in Qatar helicopter crash due to technical malfunction
Four killed as severe weather hits Oman, search continues for missing person
Japan could consider Hormuz minesweeping if ceasefire reached, minister says
