Two political groupings in the European Parliament have formed an alliance to back Antonio Tajani to become the body's next president.

The EPP Christian Democrat group and the ALDE liberals announced the agreement Tuesday. Tajani is the EEP candidate.

The EPP is the biggest group in the legislature while ALDE is the fourth-biggest. To make the coalition work, ALDE leader Guy Verhofstadt has withdrawn from Tuesday's election among the 751 legislators.

It makes the poll ever more a two-man race between Tajani and the S&D socialist Gianni Pittella.

The vote at the legislature could last all day and be spread over four rounds. The winner will head the parliament for the next two and a half years.

The election came after the withdrawal as president of S&D leader Martin Schulz.