BRUSSELS — European Union leaders pushed ahead Thursday with contested plans to send tens of thousands of migrants back to Turkey amid deep divisions over how to manage Europe’s biggest refugee emergency in decades.

With European unity fraying in the face of more than 1 million migrant arrivals over the last year, Turkey — the source of most refugees heading across the sea to Greece — is seen as the key partner to contain the influx.

The U.N. refugee agency, however, has strong reservations about asylum standards in Turkey and rights groups are concerned over Ankara’s crackdown on the media and its increasingly bloody conflict with Kurdish rebels.

But the EU feels it has no better option.

“How are you going to help Greece without having an agreement with Turkey to handle the issue? Do you really want to condemn Greece to become a refugee camp for the rest of Europe?” EU Commission vice president Frans Timmermans said ahead of the two-day summit in Brussels.

Unnerved by the hundreds of thousands of people flooding into Europe, Austria and other northern nations tightened border controls, creating a domino effect throughout the Balkans. Macedonia, just north of Greece, has all but locked its gates.

Greece, which has a vast sea border, can’t do that. So the moves have left nearly 46,000 people stuck in Greece, including some 14,000 camped out in the border town of Idomeni who are desperately hoping to move on toward Germany or Scandinavia.

Some Idomeni refugees waded through a raging stream to cross into Macedonia this week, only to be sent back bloody and bruised.

At one tent in the Idomeni mud, 29-year-old Soukeina Baghdadi sipped a coffee and warmed herself by a fire shared with neighbors. Like many, she’s hoping to move north to Germany — and hoping Europe’s leaders can help.

“All the people here are waiting for the summit, waiting for the borders to open,” she said.

Baghdadi, who is Lebanese-born but lived in Iraq with her husband, is not keen on Europe’s plan to distribute refugees like her in Greece to other EU countries.

“I don’t want to go through the relocation process, because I’m told that would mean waiting between six months and a year,” she said.

Under the EU agreement, which could be sealed with Turkish Prime Minister Ahmet Davutoglu on Friday, Turkey would stop migrants from leaving and take back from Greece all “new arrivals” not eligible for asylum.

For every irregular migrant returned to Turkey, EU countries would take in one Syrian refugee from Turkey, up to a total of 72,000, all resettled in a process supervised by the UNHCR.