The UDF governed Malawi between 1994 and 2004, and has 10 parliamentary seats. The DPP has 61 while the main opposition Malawi Congress Party has 55.
The UDF is led by Atupele Muluzi, who served in Mutharika’s government before last May’s presidential election.
Date for fresh polls set
This coalition comes a day after Malawi’s parliament set May 19 as the date for a fresh presidential election after a court overturned last year’s vote, citing widespread irregularities.
Parliament on Monday also amended the Electoral Act, another of the Constitutional Court’s orders. The amended law allows for a runoff election within 30 days if no candidate receives a majority of votes.
Mutharika and the electoral commission of the southern African nation have appealed the court ruling.
Mutharika has 21 days to decide whether to approve parliament’s decisions.
The ruling early this month was the just the second time that a court in Africa had nullified the results of a presidential election, after a Kenyan court did so in 2017.
The decision followed months of sometimes violent unrest as some in Malawi called for the head of the electoral commission to step down.
Parliament has recommended that the current electoral commissioners be replaced.