Darrell Clarke admitted his Cheltenham side are “falling at the last hurdle” in their survival bid after they went down 1-0 at home to already-relegated Carlisle.
Sam Lavelle's first-half goal was enough to seal the points for the Cumbrians, whose fate was sealed by a 2-0 defeat at Northampton last Saturday.
Cheltenham knew a win would lift them out of the bottom four for the first time since mid-August, but they came up short and Clarke admitted he is scratching his head over the performance.
“I am very disappointed with our performance and with the whole night,” Clarke said.
“Yet again, after a poor first half, I am searching for answers and I am not coming up with the right solutions at the minute.
“The group is lacking a bit of confidence, but it's no excuse and I'll take responsibility as manager.
“We are falling at the last hurdle as things stand, and that's not acceptable after working so hard to give ourselves a platform to stay in this division.
“I have to get better, the group has to get better as well and we have to give our supporters a lift come 3pm on Saturday (at home to Bristol Rovers).”
Carlisle were the better side during a cagey first half.
Joe Nuttall missed a good opportunity to give Cheltenham the lead in the sixth minute, side-footing wide after Liam Sercombe's pass.
Georgie Kelly saw a shot saved by Luke Southwood at the other end and Luke Armstrong fired wide of the near post.
Jack Armer blasted over the bar for the Cumbrians, but the deadlock was broken three minutes before half-time.
Jack Robinson's corner was headed back across goal by Ben Barclay and Lavelle touched it in from close range.
Cheltenham sent on four substitutes at half-time and changed formation, resulting in some early pressure on the visitors' goal.
But goalkeeper Harry Lewis was rarely troubled and Southwood had to fly at full stretch to keep out a looping effort from Jon Mellish in the 77th minute.
Carlisle boss Paul Simpson was pleased with his side's attitude.
“It was one of those games where we had to roll our sleeves up, put our tin hats on and defend for our lives and that's what we did,” he said.
“I was really pleased with so many things in what has been a tough time for us.
“It was a good goal and then we had to hang on because Cheltenham are fighting for their lives.
“It's a good result and makes the journey home more enjoyable. I'm still adamant I want the players to do something now at home for our fans as they've been starved of a good 90 minutes. We now have two home games to do that.
“It's been really painful what we've been through this year, but the truth is we just haven't been good enough.
“I think the players who are still here next year will be better for the experience.”
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