Humza Yousaf is to stand down Scotland's first minister once a successor is found.
He said he had made the decision after spending the weekend reflecting on what was best for the SNP, the government and the country.
Mr Yousaf had been facing two votes of no confidence in the Scottish Parliament later this week that he was not certain to win.
It follows the collapse of the SNP's power-sharing deal with the Greens.
Mr Yousaf's decision to end the agreement angered the Greens and left him struggling to secure enough support in order to lead a a minority government.
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