He will step up attacks on those campaigning to remove the UK from the EU.
Environmental campaigners hit out as party members back lifting moratorium.
The key deal over Scotland's future funding was agreed on Tuesday after months of talks.
Criminal Verdicts Bill would also have made changes to jury majorities in Scots courts.
Ms Mitchell is first Holyrood politician to speak publicly in favour of leaving the EU
Minister: Plans will ensure pregnant women and new mothers do not face discrimination.
Trade unions protest outside Holyrood amid claims councils face £350m of cuts.
Cost of telephone health service's Future Programme rose by 55%, MSPs hear.
The Boundary Commission for Scotland has begun work to redraw electoral boundaries.
The chief executive of British Gas owner Centrica also says Britain should stay in Europe.
Ministers reached an 11th-hour agreement over the Scotland Bill on Tuesday evening.
Most Britons consider themselves Eurosceptic - but it is unlikely they will vote to leave the EU.
The UK and Scottish Governments have come to an agreement after months of talks.
Nearly 200 business bosses have signed a letter backing the Stay campaign.
At least two Tory MPs at the 1922 Committee gave the warning to the Prime Minister.
Analysis: Democratic participation fund proves campaigners can make change, says Stephen Daisley.
Boris Johnson and David Cameron are now clear rivals in the battle for Britain's future in Europe.
London Mayor Boris Johnson has said the referendum is a chance to vote for real change in Britain.
The First Minister said public opinion would shift if the UK were to leave the EU.