Scotland’s first minister Nicola Sturgeon is set to resign, a senior Scottish government source has told Sky News.

The SNP leader is expected to make the shock announcement during a press conference in Edinburgh at her official residence, Bute House, at 11am.

Sky News’ political editor Beth Rigby understands the first minister will stay in post until somebody else takes over, but there is “not an obvious candidate”, raising “huge questions” for the future of her party.

The reasons for her exit are also yet to be revealed, but SNP sources have told Beth Rigby the first minister has “just had enough”.

Politics live: Sturgeon to address press conference after shock news

Ms Sturgeon has led the party and the country since 2014 after taking over from her predecessor, Alex Salmond.

She has secured election successes at every poll since then and continued to push for Scottish independence, campaigning for a second referendum on the decision.

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But it has left the first minister at loggerheads with the UK government, led by the Conservatives, who back the union.

A senior Labour source said her decision showed it was “all over” for the independence campaign, and showed “after 15 years of failure, the SNP have run out of road”.

There have been a number of tricky issues for her in recent months, including with her bill on gender recognition.

Despite passing the legislation in Holyrood, it was then blocked by Westminster, with ministers claiming it would have a “significant impact” on equalities.

Sky News political correspondent Tamara Cohen said Ms Sturgeon’s popularity “had taken an unusual knock in recent months in polls, for the first time since she became first minister”, but the news still came as a surprise.

There has also been change at the top of the SNP in Westminster in recent months, with Sturgeon ally Ian Blackford being replaced as leader in December by Stephen Flynn.