DNA match with relative is 4.27%

[Christine Shea]

I have connected with a relative identified as matching 4.27% of my DNA. I am searching for my birth father and he is the closest relative that has popped up. He thinks he's my first cousin once removed which means my birth father is his cousin. That said, there doesn't seem to be a match of his cousins. I also connected with someone at 2.12% who is the nephew of the first relative. This would mean the nephew is my second cousin.

What I'm wondering is it reasonable with 4.27% match that he is my first cousin once removed? Is that enough of a dna match? Or should I consider that my birth father may be his second cousin which totally expands who this may be but harder for my relative to pin down, as he doesn't know all his second cousins.