clutch at straws1. to try any method, even those that are not likely to succeed, because you are in such a bad situation.
He's hoping that this new treatment will help him but I think he's clutching at straws. (usually in continuous tenses)
2. to try to find reasons to feel hopeful about a situation when there is no real cause for hope. She thinks he might still be interested because he calls her now and then but I think she's clutching at straws. (usually in continuous tenses)
[TahlilGaran] English Idioms Dictionary ▲
clutch at straws{v. phr.} To depend on something that is useless or unable to help in a time of trouble or danger; try something with little hope of succeeding.
To depend on your memory without studying for a test is to grasp at straws. The robber clutched at straws to make excuses. He said he wasn't in the country when the robbery happened. [TahlilGaran] English Idioms Dictionary ▲