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DUBLIN (Reuters) - Ireland’s main opposition party rebuffed a call by Prime Minister Leo Varadkar to complete within the next month a review and potential renewal of an expiring “confidence and supply” deal that helps keep his government in office.

Varadkar’s Fine Gael party formed a minority government in 2016 under the deal with the largest opposition party, Fianna Fail, which agreed to abstain from opposition-driven votes over the course of three annual budgets.

The parties agreed to initiate talks after the last of those budgets was presented on Tuesday. But while Varadkar said he wanted to complete the review by early November, Fianna Fail leader Micheal Martin sees talks lasting until Christmas.

“We have no intention of accepting artificial deadlines or any proposal which would deny the thorough review which we envisaged when reaching agreement in 2016,” Martin told the Irish parliament on Wednesday.

“In case anyone tries to use the Brexit situation as an excuse for claiming there is instability, we have assured Ireland’s European (Union) partners of the stability of Ireland’s negotiating position and that nothing will be done to in any way interfere with a deal being done and implemented.”

Martin was referring to newspaper reports on Wednesday speculating that Varadkar could push for a December election if Britain settles differences with the European Union over future management of the Irish border to enable the United Kingdom to strike a divorce deal with the EU.

EU Brexit negotiator Michel Barnier said on Wednesday a divorce agreement with Britain was “within reach”, calling for decisive progress in the talks in time for a summit of all 28 EU leaders next week. The main outstanding dispute is over how to keep the Ireland-British border open after Brexit.

Varadkar has formally proposed extending the deal with Fianna Fail until the summer of 2020 when an election would be held. Some senior Fianna Fail members favor a shorter extension, if one is to be agreed.

Fine Gael currently lead Fianna Fail in opinion polls by a wider margin than at the last election in 2016 when it won just six more seats in Ireland’s 158-seat chamber.