Senator Bernie Sanders plans to participate in the Democratic presidential debate in April if one is held, his campaign said on Tuesday, the strongest indication yet that he plans to continue competing against Joseph R. Biden Jr. in the 2020 primary for the foreseeable future.

The Democratic National Committee has said previously that there would be a debate in April, but one has not been scheduled. The committee has not announced a media partner or a site host — critical elements that are typically agreed upon at least a month in advance. The coronavirus crisis has already upended most facets of the Democratic primary, and there is no guarantee that the debate will take place.

Still, the fact that the Sanders campaign is signaling, for now, that he would be on a debate stage in April is a strikingly public sign of the Vermont senator’s determination to wield political influence and challenge Mr. Biden for primacy despite the former vice president’s nearly insurmountable delegate lead.