Forest have only taken two points from the last 12 (Getty Images)

Despite topping the table at Christmas, Forest are now third in League One and four points off the top two.

But Arthur insists Calderwood's job is safe - at least for now.

"Colin has a job to do and that's to get us promotion and we hope he achieves that. We'll review that in the summer," he told BBC Radio Nottingham.

Interview: Nottingham Forest chief executive Mark Arthur

The next 18 matches are going to be very telling Mark Arthur

Arthur says it is crucial Forest try to bring stability to the City Ground after years of turmoil. "We've been searching for absolutely ages to have some continuity throughout the club," he said.

But failure to climb out of League One would be seen as a failure and Calderwood's future as manager would once again be called into question.

"It's unfair to make any predictions at this moment," Arthur said.