The decision comes after Saturday's 4-1 defeat at Aldershot ended the Robins' unbeaten away record and saw the club drop down to 10th in the League Two table.
Chairman Paul Baker revealed the decision has come at a decisive time with home games to come against Shrewsbury on Tuesday and Notts County this weekend.
Baker told the club's official website: "Despite a very encouraging start to the season the board were very disappointed with Saturday's performance at Aldershot.
"The board have therefore given Martin a small additional budget to bring in one or two loan signings. The money is being provided by the directors themselves.
"Hopefully this will give the squad a boost ahead of two very important games and Martin will be trying to get someone in within the next couple of days."