Robert Kennedy Jr. is planning to drop out of the presidential race by the end of this week, sources familiar with the decision tell ABC News.

Sources say Kennedy is leaning toward endorsing former President Donald Trump, though the sources cautioned the decision is not yet finalized and could still change, with one source adding Kennedy's hope is in part to finalize things quickly in order to try to blunt momentum from the DNC.

This is a developing story. Please check back for updates.