Plaid Cymru has pulled out of its co-operation agreement with the Welsh Labour government.
The two parties signed up to the three-year deal in 2021, agreeing to work together in a raft of policy areas in the Senedd.
However, the smaller partner has now withdrawn with immediate effect, seven months before the agreement was due to officially end.
Politics live: Co-operation agreement in Wales comes to abrupt end
In a statement, Plaid’s leader Rhun ap Iorwerth said he was “proud of the way in which the agreement demonstrated a new way of doing politics which focused on areas of policy which impact people’s everyday lives”.
But he said he remained “deeply concerned” that Labour First Minister Vaughan Gething had failed to pay back a controversial £200,000 donation, and was “worried by the circumstances” around the sacking of Welsh minister Hannah Blythyn this week after a row over a leaked text message.
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“I am also concerned by the emerging approach of the government in relation to some elements of the co-operation agreement, including the decision to delay action in supporting the poorest families in our communities, as evidenced most recently by the decision to delay council tax reform,” added Mr ap Iorwerth.
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“Plaid Cymru will move onwards with a clear and continued commitment to scrutinising Labour’s record, and with a renewed determination to put forward bold ideas which match the people of Wales’s ambitions for our country.”
Mr Gething released his own statement, saying: “While it was always a time limited agreement, we are disappointed Plaid Cymru has decided to walk away from their opportunity to deliver for the people of Wales.”
After thanking the Plaid members of the Senedd he had worked with, Sian Gwenllian and Cefin Campbell, he said Welsh Labour would now “look closely at how we can progress the outstanding co-operation agreement commitments” around language education and housing.
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The two parties agreed to work on almost 50 policy areas when the deal was first signed in 2021, after Welsh Labour won 30 of the 60 seats at the last Senedd elections – failing to get an outright majority.
It fell short of a formal coalition agreement, like that signed between the Conservatives and Liberal Democrats in Westminster in 2010, or the power-sharing deal made between the SNP and Green Party that recently collapsed, with none of the 13 Plaid members serving as ministers.
The agreement bore fruit, however, with policies around free school meals and energy passing through the parliament – which both leaders praised in their statements.
But there had been some reports in recent months that Plaid was looking to pull out of the deal, with Mr ap Iorwerth telling the BBC his party had “every right to discuss the length of the deal” ahead of its official end in December.