It comes after a weekend poll showed the Tories had recovered after a dip in Scotland and could retain all or most of their 13 seats in Scotland. The SNP, though, is poised to make significant gains and could take upwards of 40 of the country's 59 seats.
Mr Brown hit the campaign trail in Auchterarder, along with SNP candidate John Nicolson who is seeking to win the Ochil and South Perthshire seat.
"Only a vote for the SNP can help Scotland escape Brexit, lock the Tories out of power and put Scotland’s future in Scotland’s hands,” Mr Brown said“And only the SNP can beat the Tories in Scotland. The prospect of five more years with Boris Johnson as Prime Minister will fill most Scottish voters with horror.“After a decade of Tory austerity, Boris Johnson’s miserable plan is for more of the same – plus dragging Scotland out of the EU against our will."
The SNP will launch their manifesto this week. Although they have ruled out a coalition with other parties, Nicola Sturgeon has indicated that her MPs could be ready to back a Labour administration if Jeremy Corbyn grants a transfer of power to Holyrood for a second referendum on independence.
Mr Brown added: “If we face another hung parliament, Scottish votes could determine who forms the next government.“And, with the SNP as the challengers in every Tory held seat – and polls showing Labour trailing behind in third place – only SNP MPs can deprive Boris Johnson of a majority.“Voting SNP is the key to locking Boris Johnson out of power.”