A second Scottish National party MP has defected to the Alba party, which claims it can deliver a pro-independence super-majority in May’s Scottish parliament elections, as the Scottish Greens dismissed Alex Salmond’s new political venture as being “thrown together at the last minute by a man who is less popular in Scotland than Boris Johnson”. Neale Hanvey follows the East Lothian MP, Kenny MacAskill, in joining the newly formed party, having previously been suspended by the SNP for using antisemitic language on social media. He apologised for any offence caused in the days following his suspension. As the SNP set out eye-catching campaign pledges for young people – that every schoolchild will receive a new computer device and no-one under the age of 21 will have to pay council tax if the party is re-elected – the polling expert John Curtice said Alba could deprive Nicola Sturgeon of the Holyrood majority she was seeking as a mandate for a second independence referendum. The latest developments come at the end of a turbulent week in Scottish politics, which began with Sturgeon being vindicated by an independent inquiry into whether she broke the ministerial code in her meetings with Salmond about the Scottish government’s inquiry into sexual harassment complaints against him, and ended with the former SNP leader launching his bid to return to Holyrood as an MSP for the new list-only party. Asked by the BBC’s Andrew Marr on Sunday whether the Alba party could take votes from the Scottish Greens, who have benefited in the past from SNP constituency voters giving them their regional list preference, their co-leader Lorna Slater said: “We are not competing for the same voters”. “Scottish Green voters care about the climate, about fairness, human rights, the kind of policies we’ll be bringing forward … they are a totally different demographic from people who are likely to vote for a party thrown together by a disgruntled ex-first minister as part of his vendetta against our first minister.” Curtice, a professor of politics at Strathclyde University, told BBC Radio Scotland’s Sunday Show that polling evidence suggested Salmond “is not a very popular politician any more”, but added the new party could “make all the difference” to whether the SNP won an overall majority. Under the Holyrood electoral system, 73 MSPs are elected to represent constituencies under a first-past-the-post ballot, with the SNP expected to win most of those seats in May. The remaining 56 MSPs are elected by a regional list system, designed to make the seat distribution more representative of the overall vote. In 2016, the SNP did so well in constituency voting that it won list seats in only two of the eight regions, south of Scotland and Highlands. Alba candidates will run only on the regional lists, which Salmond has argued would scoop up previously “wasted” list votes for the SNP. Curtice said: “The risk to the SNP is that if Salmond gets 4% or 5% of the vote, particularly in those two crucial regions, and those come from the SNP, he may put them down a peg, lose them one or two seats and as a result make all the difference between an overall majority or not.” In an interview with Scotland on Sunday, Sturgeon repeated her concerns that “serious questions” about the appropriateness of Salmond’s return to elected office. “One of the things that has irritated me, because it reduces the seriousness of what it being dealt with, is the description of this as a Salmond-Sturgeon row as if we just had a falling out about some political issues. He was accused of really serious misconduct.” In his defection statement, Hanvey said the new party was “a tonic for our movement”. “Like so many, I have been angered by our powerlessness in the face of Brexit and share the frustration of many who feel the aspirations of the independence movement are being ignored.” Hanvey’s was one of a handful of high-profile moves from the SNP to Alba over the weekend, including the former MP Corrie Wilson and two councillors, Lynne Anderson and Caroline McAllister, who were both elected to the national executive committee last November as part of an internal rebellion against Sturgeon’s leadership style and have been outspoken critics of policy on transgender issues. MacAskill, a former Holyrood justice secretary, announced his defection on Saturday, meaning the Alba party now has more MSPs than Scottish Labour. Asked by Sophy Ridge on Sky News if such moves indicated nationalist infighting, he denied this, saying: “This is about delivering that independence super-majority. The independence movement is a broad church, it encompasses more than one political party. “We believe that the time has come for that independence movement to come together, be reflected by more than one political party to ensure it is the Scottish people who prevail and who decide and that it is the Scottish parliament that confronts Boris Johnson after 6 May.” Asked whether he agreed with Sturgeon’s suggestion that Salmond still had questions to answer regarding his personal conduct, MacAskill said: “No. We’ve had two court cases – he has been successful in both a civil and indeed a criminal court action. That is behind us, we go forward.” Scottish Labour said the defections showed the SNP was in “utter disarray”, while the Scottish Conservative leader, Douglas Ross, continued to urge other pro-union parties to work with the Tories, as happened with the Better Together campaign in 2014. On Saturday, this offer prompted the Scottish Labour leader, Anas Sarwar, to tell Ross to “grow up”.