SNP
Scotland's finance secretary would not have supported equal marriage as a “matter of conscience”.
The cabinet secretary for finance and the economy is widely seen as a frontrunner in the race to replace Nicola Sturgeon.
Humza Yousaf, Angus Robertson and Kate Forbes are all likely contenders.
Stephen Flynn says the special party conference which was due to debate next steps should be "paused".
The SNP leader's decision to resign could rejuvenate the campaign to break up the UK.
The outgoing leader said the SNP was "awash with talented individuals" who could replace her.
The SNP leader denied she was leaving over "short term issues" such as the transgender rights row.
Scotland's first minister is facing challenges on all fronts as she approaches a decade in power.
It would be the first time a UK government has taken the dramatic step in nearly 25 years of devolution.
Stephen Flynn also dubbed Prince Harry's comments about his time in Afghanistan "disgusting".