The Biden campaign was even quite forceful in its statement

Joe Biden looks forward to facing Donald Trump in a multi-debate series that the American people have come to expect from their leaders; we hope that President Trump would not break that tradition or make excuses for a refusal to participate

Our position is straightforward and clear: Joe Biden will accept the Commission’s debates, on the Commission’s dates, under the Commission’s established format and the Commission’s independent choice of moderators

Any ‘debate proposals’ in lieu of that are just an effort to change the subject, avoid debates, or create a distracting ‘debate about debates.'

The Trump position seems to be saying that he will debate if he can pick the moderators: clearly the President, who largely conducts interviews only with favorable news outlets, is afraid of facing questions from a neutral moderator