Poland said Saturday it was proposing a Polish Euro-MP for the EU presidency to succeed Donald Tusk, whose second term is opposed by the governing rightwing Law and Justice party (PiS).
Tusk, who has been president of the European Council since December 2014, had so far been the sole candidate.
"The Polish government proposes the candidacy of Jacek Saryusz-Wolski for the presidency of the European Council," the foreign ministry said in a statement.
Tusk, a centre-right Polish prime minister from 2007 to 2014, has been sharply at odds with Poland's rightwing government over a range of issues including changes to state media and the constitution.
He became president of the European Council, gathering EU heads of state or government, after a Belgian, Herman van Rompuy.
The Council meets in Brussels next Thursday to discuss whether to give Tusk a second term after his first mandate expires on May 31.
The issue may also be raised Monday when French, German, Italian and Spanish leaders meet in Versailles, France, to discuss the future of the EU, French diplomatic sources said.
Saryusz-Wolski, 68, an MEP since 2004, is a member of the European People's Party (EPP), gathering Christian Democrat and centre-right parties.
Within the constellation of Polish politics, he is a member of the opposition Civic Platform, although the centrist group has recently distanced itself from him.
After Saturday's announcement, Civic Platform expelled Saryusz-Wolski from its ranks, which will trigger his exclusion from the EPP group.
- Rival candidate doomed -
Tusk's problems with PiS stem greatly from a vitriolic relationship with party boss Jaroslaw Kaczynski.
Kaczynski accuses him of bearing "moral responsibility" for the death of his twin brother Lech Kaczynski, who was then president, in an air disaster in 2010 that also killed 95 others.
When the PiS -- which supports the theory the plane was brought down in an attack -- took power in October 2015 it re-opened the inquiry into the causes of the disaster.
Kaczynski has long said that he believes foul play caused the crash. Polish and Russian investigators have never found any evidence to support the claim.
Tusk seems to have support among a majority of European leaders for a second term. Poland by itself cannot block a second term as approval does not require unanimity.
"Mr Tusk should not be the victim of his own country's bid to dismiss him. That wouldn't be right," a French diplomatic source said.
"Tusk is in a very strong position," a European diplomat said.
He also said Tusk did not need his country's backing to run for a second term. He has already met the sole condition to run -- by confirming his will to do so during a recent summit in Malta.
EPP chief Joseph Daul tweeted that "the EPP family stands fully behind" Tusk.
- EU-Polish friction -
Even though the EU appears set to rally around Tusk, Poland's move shows the extent of Warsaw's animosity towards him.
The EU and Poland have been at loggerheads over a series of policies introduced by the PiS, including a string of judicial reforms that saw critics take to the streets in large demonstrations.
"I can't imagine supporting a candidate who fights against his own government. I also can't imagine that the other EU member states would support a candidate who doesn't have the support of his own government," Polish Foreign Minister Witold Waszczykowski said Saturday.
The foreign minister also said Saryusz-Wolski was in Brussels to try to rally support for his candidacy.
An attempt at a Warsaw meeting on Thursday to secure the support of the so-called Visegrad 4 nations -- the Czech Republic, Hungary, Poland and Slovakia -- ended in failure.