In August 2019, after the selection of Boris Johnson as Prime Minister of the United Kingdom, O'Toole proposed to get Parliament to back an alternative Cabinet who would push back the October deadline for Brexit to allow a trade deal to be negotiated. The proposal required seven Sinn Féin MPs in northern Irish border constituencies to resign in favour of a pact between the four largest anti-Brexit parties in Ireland, thereby triggering by-elections at a certain date in mid-September. O’Toole believed they would result in a more hardline anti-Brexit parliamentary faction that would make a stronger case for a no-confidence vote in Johnson. The proposal received sharp criticism from Sinn Féin leader Mary Lou McDonald, who claimed the existing anti-Brexit factions in Parliament were strong enough without the party making too many policy concessions.