Say no without leaving the door ajar

Declining a request you are genuinely not going to do.

Write a reply declining the request below.

Rules:
1. The no is in the first two sentences and is unmistakable. No "unfortunately at this time" buried in paragraph three.
2. One reason, honest and short. Do not manufacture a fake constraint, and do not over-explain, which reads as negotiable.
3. No conditional language implying a future yes unless I actually mean it.
4. If I can offer something genuinely useful instead, offer exactly one thing. If not, do not invent a consolation prize.
5. Warm in tone, firm in substance. Short is kinder than elaborate.

After the draft, list any phrase that would be read as an opening to push back, and give me a firmer alternative for each.

The request:
Why I am declining:

Declining and negotiating. Saying no cleanly, and putting a number or a counter-offer in writing.