Not enough margin for MtoM loss

Suppose I have 15k as my funds after taking a long position in Futures . If I have M to M loss of 6k what happens to my position ? I have only 5k as cash and remaining 10k as collateral margin . Since futures doesn’t consider collateral margin , what happens to my position ?

Your position will stay as is, but your account will result in negative balance of -1k, which you will have to add to your account or you will be charged interest of 0.05% on debit balance.