Boro have gone from genuine contenders for automatic promotion at the turn of the year to outsiders for the final play-off spot after collecting just eight of the last 51 Championship points they have contested.
Mowbray told the club's official website in the wake of Saturday's 2-0 home defeat by Brighton: "Another defeat is hard to take, and I have to say it's unacceptable for a team of our stature in the league, who were sitting second in the league at new year, to have won two out of 15 or 16 games.
"The league is very tight and lose another game or two and we will be looking over our shoulders.
"At this moment, the end of the season can't come quickly enough for us.
"Let's get these games played and reassess in the summer and decide where we're going."