Isamaa Riigikogu member Aivar Kokk said the party will support presidential candidate Alar Karis in the second round of voting on Tuesday.
Speaking to ETV, he said: "I know that our party's members have all promised to support the presidential candidate, so if the coalition votes are there, the votes should be there together," Kokk said.
The Social Democratic Party (SDE) has also agreed to support Karis, who needs 68 votes to be elected president. Yesterday, he received 63.
Isamaa have 12 votes and SDE 11. The coalition parties, Reform and Center, who nominated Karis, have 59 between them.
Editor: Helen Wright