The prime ministers of Spain, Belgium, Ireland and Malta have called on European Council President Charles Michel to have a “serious debate” this week about the Israel-Hamas conflict in Gaza, according to a letter seen by POLITICO.

“We must call urgently for all the parties to declare a lasting humanitarian cease-fire that can lead to an end of hostilities,” the four leaders wrote. “It is time for the European Union to act. Our credibility is at stake.”

This week’s European Council summit is set to focus more on Ukraine, as the EU hopes to make a historic decision on starting talks to bring Kyiv into the 27-nation club and seal a key budget deal that would throw a €50 billion lifeline to the country’s flailing war economy.

But given the scale of the devastation in the Middle East, the four leaders called it “imperative for us to hold a serious debate on the war” at the summit. “We call on your leadership to steer such a discussion, which should aim at agreeing on a clear and firm position by the European Union,” they told Michel.

The EU has so far struggled to forge common positions on the Middle East conflict. In draft conclusions for the upcoming leaders’ summit, seen by POLITICO, there is no paragraph yet on Gaza, showing the difficulty of agreeing on common language among the 27 capitals.

At the last EU leaders’ meeting in October, they agreed to call for “humanitarian pauses” in the Middle East.

One EU official said the letter is likely to complicate the debate even more, given how divisive the issue already is within the bloc.