A spokesman for Shadari did not respond to a request for clarification, Kabila has repeatedly dodged the question and government spokesman Lambert Mende told reporters on Monday he was "not aware of a plan to change the constitution".
Kabila is unpopular in the capital Kinshasa and many parts of the country. A rare poll released in March showed that eight in 10 Congolese have an unfavorable opinion of him. Scores have died in protests since he refused to step down when his mandate expired 18 months ago.
Militias have proliferated, killing and displacing villagers, kidnapping foreigners and shutting down eco-tourist spots. The violence has hit mining operations in Africa's top copper producer and the world's leading miner of cobalt, prized for batteries for electric vehicles.
"LEGAL BASIS"
Earlier this month, Kabila appointed three new judges to the Constitutional Court, including two close allies.
His opponents fear the court will legitimize running again on a legal technicality - the fact that electoral procedure in the constitution has changed since Kabila was first elected in 2006, although the two-term limit was there before.
"The legal basis that legislated the 2006 elections was different from the one of the 2011 elections," legal expert Jean-Cyrus Mirindi, a Kabila ally, told a debating forum in Kinshasa late last month.
Long before the changes, the court had ruled when Kabila's mandate expired in 2016 that he could stay on until the poll.
Another option for Kabila is to hold a referendum, as his allies have sometimes suggested and as the presidents of neighboring Rwanda and Congo Republic did.
Resistance could come from Congo's Catholic church, which has slowly transformed from a mediator for peace to lightning rod for dissatisfaction with Kabila.
Donatien Nshole, spokesman for the church council, told a news conference this week "the bishops will never support" a Kabila third term.
It would also set Congo on a collision course with Western powers and its neighbors - both of which have a history of meddling in its affairs. Wars between 1996 and 2003 sucked in nine African armies and killed millions.
French President Emmanuel Macron met with Rwandan President Paul Kagame last week and Angolan leader Joao Lourenco on Monday to discuss Congo, infuriating Congolese authorities.
Rwanda and Angola fought on opposite sides during a 1998-2003 war, but both are increasingly alarmed at Congo's slide toward instability.
"Congo ... will not let any person, state or interest group ... substitute itself for the Congolese people in deciding its future," government spokesman Mende said on Monday.
*Source Reuters