Midfielder King comes back into the reckoning after missing the defeat at Peterborough while on international duty with the Wales Under-21 side.
Elsewhere, Wayne Brown is in contention to start after being on the bench at London Road. He will challenge Patrick Kisnorbo and Michael Morrison for the right to partner Jack Hobbs at the heart of defence.
The League One leaders saw second-placed Peterborough narrow the gap at the top of the table to just four points with a 2-0 victory in last week's meeting between the two sides.
Ian Harte has been ruled out as Carlisle seek to end a six-match winless run and enhance their survival prospects.
The 31-year-old former Republic of Ireland international defender visited a specialist on Wednesday after fracturing two bones in his hand as he made his debut in the 1-1 draw with Northampton.
The left-back was told he will need a full cast for at least two weeks and is unlikely to return before the April 18 clash with Swindon.
Ian Morris, who also made his debut against the Cobblers, is set to continue in midfield, but United will be without striker Gareth Taylor, who has returned to Doncaster following the end of his loan spell.
Goalkeeper Chris Howarth is out for the season after breaking his leg in a reserve-team game on Monday.
Peter Murphy could come back into contention after a back problem, but Paul Thirlwell, Danny Livesey and Marc Bridge-Wilkinson remain out.
Sporting Life