Why would Putin agree to a ceasefire. He's winning. If Zelensky gives him Odessa, he may consider it.
It's not only the total refusal on the part of the Biden Administration to even admit the possibility of opening up negotiations, it's the fact that Biden has actually scuttled any attempts at a negotiated end to the war. No cease fire for Ukraine, which is losing badly and may soon be over run, but ceaseless pressure for a cease fire in Gaza where Israel is winning.