Sources say a deal is close but discussions are more complex as provisions are thrashed out amid the possibility Newcastle get relegated.
United have not shown any more interest in Trippier, 31, after they attempted to sign him in the summer. Diogo Dalot has started in four of the last five Premier League games and earned plaudits for his performances.
United kept Dalot as Atletico outpriced them for a move for Trippier, who started for England in the European Championship final against Italy.
Roma had expressed interest in Dalot last month but his regular playing time heading into January leaves United with two first-team-ready right-backs.
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