Nicola Sturgeon is to promote a message of “hope and optimism” in her speech to the SNP conference in Glasgow.
The party leader and first minister will close the three-day event by hitting out at “unfolding calamity” and “despair” at Westminster.
She will contrast this by painting an independent Scotland as “a beacon of progressive values”.
Ms Sturgeon will also set out a “fair work first” approach to business support grants and contracts.
The SNP leader kicked off the conference by announcing that the party’s 35 MPs at Westminster would vote in favour of a new referendum on Brexit, were such a question to be tabled at Parliament.
This was endorsed by members via a topical resolution, with the party also promoting its policy of the UK remaining in the EU’s single market and customs union.
Ms Sturgeon will return to the constitutional theme in her speech, saying that an independent Scotland could offer “equality, opportunity, diversity and fairness”.
She will say: “The Westminster government stumbles from day to day and disaster to disaster. It’s hard to watch that unfolding calamity and feel anything other than despair.
“So it is up to us – now more than ever – to offer optimism and hope.
“Just think how much more hope will be possible when we take Scotland’s future into Scotland’s hands and become an independent country.”
The UK government has placed itself in opposition to a second referendum either on independence or on Brexit.
The prime minister’s official spokeswoman said Scotland “had an independence referendum four years ago and voted decisively to remain in the UK”, adding that “now is not the time” for a fresh vote.
Earlier on Tuesday, the Scottish government’s Brexit secretary, Mike Russell, urged activists to be patient over a second independence referendum, which he said should only take place when voters are “persuaded, ready and determined to win”.
He said: “Our job as a party and as a government is to both make sure that Scotland flourishes, no matter the circumstances but also to ensure that – at the right moment – the choice of independence can be made.
“The right moment – not the most comfortable moment or the moment that best relieves our natural impatience. The moment at which our country is persuaded, ready and determined to win.”