NAIROBI, Kenya (AP) – Ethiopia’s Tigray forces on Friday joined with other armed and opposition groups around the country in an alliance against Prime Minister Abiy Ahmed to seek a political transition after a year of devastating war, and they left the possibility open for his exit by force.

“There is no limit for us,” Berhane Gebrechristos, a former foreign minister and Tigray official, told reporters in Washington. “Definitely we will have a change in Ethiopia before Ethiopia implodes.”

The alliance includes the Tigray forces who are fighting Ethiopian and allied forces, as well as the Oromo Liberation Army fighting alongside Tigray forces and seven other groups. The Tigray fighters are approaching the capital, Addis Ababa, according to the State Department, and Ethiopia on Friday called on military veterans to join what it now calls an “existential war.”

The U.S. Embassy is urging citizens to leave Ethiopia “as soon as possible.”

The opposition alliance forms as U.S. special envoy Jeffrey Feltman is in Ethiopia’s capital meeting with senior government officials amid calls for an immediate cease-fire and talks to end the war that has killed thousands of people since November 2020. The U.S. said he met with the deputy prime minister and defense and finance ministers on Thursday. It was not clear if Mr. Feltman would meet the prime minister, who met with UN humanitarian chief Martin Griffiths on Friday about the rapidly growing crisis.

Secretary of State Antony Blinken in a statement again appealed for a cease-fire and talks, and called on the Tigray and Oromo Liberation Army forces to “immediately stop the current advance towards Addis Ababa.” He also urged Ethiopia’s government to halt its military campaign, including airstrikes in Tigray, and the mobilization of ethnic militias.

The new United Front of Ethiopian Federalist Forces seeks to “establish a transitional arrangement in Ethiopia” so the prime minister can go as soon as possible, organizer Yohanees Abraha, who is with the Tigray group, told The Associated Press. “The next step will be, of course, to start meeting and communicating with countries, diplomats and international actors in Ethiopia and abroad.”

He said the new alliance is both political and military. It has had no communication with Ethiopia’s government, he added.

A spokesman for the Oromo Liberation Army, Odaa Tarbii, said the possibility of forcing the prime minister out will depend on Ethiopia’s government and events over the coming weeks. “Of course we prefer if there’s a peaceful and orderly transition with Abiy being removed,” he said.

“The goal is to be as inclusive as possible. We know this transition requires all stakeholders,” he added. But as for members of the prime minister’s Prosperity Party, “there would have to be a process. Many members would have to go through investigation, possibly be prosecuted” for crimes related to the war.

Ethiopia’s government called the alliance “a publicity stunt,” asserting that some of the groups involved “are not really organizations that have any traction.” It also asserted that life in the capital had a “sense of normalcy” and rejected any notion of a siege.

The prime minister’s spokeswoman, Billene Seyoum, addressed the alliance when she tweeted that “any outliers that rejected the democratic processes Ethiopia embarked upon cannot be for democratization,” pointing out Mr. Abiy’s opening-up of political space after taking office in 2018. His reforms included welcoming some opposition groups home from exile.

The OLA spokesman, replying to the tweet, noted that some of the people who returned to Ethiopia were later put in prison or under house arrest.

“A lot of goodwill was lost over the last three years,” he said.

Other groups in the alliance include the Afar Revolutionary Democratic Unity Front, Agaw Democratic Movement, Benishangul People’s Liberation Movement, Gambella Peoples Liberation Army, Global Kimant People Right and Justice Movement/Kimant Democratic Party, Sidama National Liberation Front and Somali State Resistance.

It is not clear whether all the groups are armed. But there is interest in protecting the 1995 constitution that enshrines ethnic federalism and includes the right to self-determination. Under the constitution, critics have accused regional leaders of asserting the rights of majority ethnic groups at the expense of minorities.

Mr. Abiy preached national unity and transformed the former ruling coalition of ethnic-based parties into a single Prosperity Party, but the Tigray leaders who long dominated that coalition opted out, deepening frictions that led to war.