Conte reportedly spent the past two months haggling with Matteo Renzi, the leader of his minority coalition partner Italia Viva, over how to spend 209 billion euros ($254 billion) in EU grants and loans.
Renzi, a former prime minister who once headed the second-largest Democratic Party, said Italia Viva was ready to pull its two ministers from the government after the vote, set for 9:30 p.m. (20:30 GMT).
"When the text arrives we will assess it and decide whether to abstain or vote in its favour… but immediately afterwards we will do what we must do," he was quoted as saying by the Corriere della Sera daily.
Italia Viva's departure is likely to strip Conte of a working majority in parliament and trigger a vote of confidence in his government.
A possible scenario if Renzi follows through on his threat would be for the prime minister to initiate a cabinet reshuffle, giving the coalition partner more government seats.
Vito Crimi, who leads the parliament's largest Five Star Movement party, told the Ansa news agency that he would treat Italia Viva's exit as sabotage and would object to its return to the government.