The Black Cats remain third in League One following Saturday's 1-1 draw with Luton, but do have a game in hand on the sides above them.
Donald revealed last week that the Black Cats are looking to sign another striker in January, while the club have submitted a second bid for Wigan forward Will Grigg.
But, as the transfer window reaches the halfway stage, Sunderland have added just one player to their squad this month, following Jimmy Dunne's arrival from Burnley on loan.
And Donald, who has been open with fans ever since he bought the club back in May, has made a move to reassure supporters on social media.
Watch shocking footage of drink and drug driver who caused death of young dad Richie Jordan as partner Carol King pleads for others not to make same mistake
Man arrested after collision leaves 13-year-old boy in critical condition
Sunderland rapist jailed for life as victims reveal horrific ordeal
The 13 places where most crime was reported across the north of Sunderland in June
Thunderstorms: When does the Met Office think thunder and lightning hit Sunderland this week and what does the yellow weather warning mean?
When asked if there is any news regarding in and out-goings at the Stadium of Light, Donald tweeted:
"We are working very hard to do the right deals. I know everyone wants everything sorted asap but we need the detail right. We know we need to strengthen - we have sensible & serious offers out in the market. We will definitely be backing Jack - just need a little time."
Sunderland's only other significant piece of business this month saw forward Jerome Sinclair return to Watford following a loan spell at the Stadium of Light.