The under-pressure Portuguese wants to see if Uniteds board are willing to put enough faith in him to sanction what would be big-money deals, according to ESPN.
Mourinho has come under pressure after a disappointing start to the season that sees his team seven points behind Premier League pacesetters Manchester City, Liverpool and Chelsea, despite a comeback win over Newcastle last weekend.
United dismissed widespread reports over the weekend which claimed Real Madrid coach Zinedine Zidane had been lined up as Mourinhos replacement, but according to the report Mourinho wants public support with money to spend during the window — funds he believes he should have been given in the summer.
United signed midfielder Fred, full-back Diogo Dalot and goalkeeper Lee Grant for a combined fee in the region of £70m, but crucially failed to sign a defender despite heavy links to Toby Alderweireld, Harry Maguire and Diego Godin, among others.
The report says Mourinho has used that failure to justify Uniteds poor start to the season.
The United boss failed to convince the board to spend big on his centre-back targets because they were all nearing the latter stages of their career, whereas Inter Milans Skriniar and AC Milans Romagnoli are both 23, with Mourinho increasingly hopeful moves for the pair will be sanctioned.
The pair would be available to play in the Champions League knockout rounds this season, with each being valued by their respective clubs in the region of £40m.