As a rule, endorsements do not impress me one way or the other. Celebrity endorsements I find to be totally useless. Why should we assume that they know more than the rest of us.
Endorsements from fellow party members, is just part of the game.
If someone outside the inner circle and has a reputation for being an informed person who has voiced his own views in the past on other issues, might get some attention. Those situations are rare.
I like a lot of the Hollywood celebrities, but I usually do not agree with their politics.
I might like a particular senator or representative, but if he is supporting a person who happens to be in his same political party, I have to closely questioned it. We had a congressman from my area, who was elected to fill an uncompleted term. He cast several votes that went against the majority view of the area and in less than a year. When the election came for the next two-year term, he came in third. He had a flurry of endorsements. They did not do him any good.