If all coalition delegates follow their party leaders, Wulff can easily win an absolute majority in the first round of secret ballot to become new President.

Christian Wulff resigns as premier of state Lower Saxony at the Reichstag in Berlin, capital of Germany, on June 30, 2010. Christian Wulff, nominated by Merkel's coalition government, won the President election on Wednesday evening after three ballots. [Achim Melde/Xinhua]

However, Wulff only got 600 votes in the first ballot and 615 votes in the second, lower than the 623 votes needed to win the election, forcing the Federal Assembly to make the third ballot.

The election "didn't show the unity of the coalition," said by Wolfgang Bosbach, a delegate from Merkel's Christian Democrats after the second ballot.

Besides the frictions within the coalition, clear differences can also be observed in the opposition parities during this election

In the first and second ballots, Luc Jochimsen from the Left party won 126 and 123 votes separately, while Gauck from the Social Democrats (SPD) and the Greens won 499 and 490 votes. If these three opposition parties can united, Wulff will face serious challenge in the election.

However, during the third ballot, although Jochimsen withdrew, both she and Gregor Gysi, the Left party leader in parliament still called for its members to abstain instead of supporting Gauck from Social Democrats and the Greens.

"I have decided to withdraw," Jochimsen said. "But I've always said that both are not electable for us. Therefore our position in this political situation is to abstain," she added.

"Obviously I would imagine that neither conservative candidate is considered electable by our members," Gregor Gysi said.

The Federal Assembly must elect President within three ballots. A candidate must win an absolute majority, more than 50 percent of the votes, to win the election in the first and second ballots, while in the third ballot, a candidate who got a relative majority will become President.