Scottish Labour leader Anas Sarwar has accused John Swinney of running a "dishonest and disgraceful" campaign ahead of last week's Holyrood by-election.
Sarwar claimed the SNP were pushing voters to Reform UK through their tactics, which he described as "shameful" on BBC Scotland's Sunday Show programme.
But Swinney justified his "two-horse race" remark by saying Labour's vote share had "collapsed" in the by-election and that his party's own data showed a surge for Reform.
Scottish Labour won an unexpected victory in Thursday's by-election as Davy Russell took the Hamilton, Larkhall and Stonehouse seat.
The first minister also told the programme he would consider a reshuffle of his cabinet "in due course" following the defeat, which saw the SNP lose a seat previously held by the late Christina McKelvie.
