The EPP group was able to rally the liberal Alde group not only behind its candidate for European Parliament presidency, Antonio Tajani, but also behind a second term for Donald Tusk.

"The EPP and Alde support the prolongation of the job of Donald Tusk. He has a strong personality and is a former prime minister and did a great job for Europe striking political balances, especially on migration. That's why we want him to continue the job," Weber said.

EPP and Alde on Tuesday signed a "pro-European pact", in which Tusk's candidacy was not mentioned.

Janusz Lewandowski, head of the Polish EPP delegation, said the endorsement was part of a broader understanding.

"The written part could only deal with organising the work of the European Parliament," he told Polish journalists.

Asked if the parliament really could influence a decision which would be taken by EU heads of state, Weber said: "We are the European Parliament, but we have networks in the council. Guy Verhofstadt is well-connected with the seven liberal prime ministers, he confirmed with his signature that he will fight for Donald Tusk."

Hans van Baalen, a Dutch liberal MEP who is president of the Alliance of Liberals and Democrats for Europe (Alde) party, the pan-European gathering of liberal parties, and coordinates the liberal prime ministers in the EU, confirmed to EUobserver that Tusk had the liberals' backing.

"We have no problem with Tusk. This has been re-established in this deal," Van Baalen said.

The news could upset the parliament's socialist group, which campaigned against Tajani saying that the EU leadership must reflect the results of the European parliamentary elections.

The social-democratic S&D group is the second largest of the house, with 189 MEPs.

"Our position, which is well-known, is that there can be no balance of power when the EPP has three institutions. But regarding Tusk, it is not up to us, but to the member states," S&D spokeswoman Utta Tuttlies told EUobserver.

It will be difficult for the socialists to do anything about it, since they only head seven EU member states. EPP has nice, while the liberals have also seven.

The council president is elected for a 2.5 year term, which is renewable once, by a qualified majority, meaning that 16 out of 28 member states representing at least 65 percent of the total EU population must back the candidacy.

One council official told this website that there was no appetite in the council to look for alternative candidates.

"I don't think EU leaders want to open that issue now," the official said, referring to Brexit talks and the election of Donald Trump as US president.

But weighting against Tusk is the fact that he lacks the support of his own government, the conservative Law and Justice party.

The minister of foreign affairs, Witold Waszczykowski, recently called Tusk an "icon of evil".

It would be highly unusual that the council president would be elected despite the lack of support of his home country, but Poland does not need to actively approve the bid.

Tusk himself said remained tightlipped on the election.

"Don't fear, everything will be fine," he told reporters after a parliament debate on Wednesday.