THE number of candidates vying to be Nicola Sturgeon’s SNP deputy has risen to four, with Edinburgh East MP Tommy Sheppard the latest to throw his hat into the ring.

He is standing on a platform of campaigning for a second referendum and internal reform.

MEP Alyn Smith, who received a standing ovation in Brussels last month for a passionate defence of Scotland’s place in Europe, also formally announced he was running yesterday.

News of Smith’s intentions leaked mid-week, but last night he confirmed he would launch his campaign in Edinburgh on Thursday.

He will also unveil a website, alyn4depute.eu, and a crowd-sourcing drive to secure the 100 signatures needed from 20 SNP branches to qualify as a candidate.

Inverclyde councillor Chris McEleny and SNP Westminster leader Angus Robertson have already announced bids to replace MP Stewart Hosie as SNP depute leader in October.

Robertson has also made Brexit and Europe a key focus, while McEleny has highlighted the importance of local government ahead of next year’s council elections.

Hosie quit in May after it emerged he was having an affair with freelance journalist Serena Cowdy, who was previously in a relationship with SNP MP Angus MacNeil.

Smith, 42, said his pitch to the SNP’s 116,000 voters would focus on strengthening Scotland’s ties with Europe in the wake of the Brexit vote - something he would be able to work on day-in, day-out as an MEP in Brussels.

A member of Sturgeon’s Standing Council on Europe, Smith told the Sunday Herald: “If we’re serious about, then we need to do Europe in Europe.

“We need to reach out to Brussels and the main state capitals and prepare.

“We also need to cohere a new Yes movement around the SNP.”

Writing on his blog this weekend, Sheppard, 57, said the SNP had to shake up the way it ran its internal affairs if it was to win the next independence referendum.

He said recent electoral success had been “made easy” by weak opponents, and future challenges “including Indyref2 when it comes” would be a “far tougher test”.

To achieve independence “our party needs to be even better at everything it does”, he wrote.

He said he wanted “much more political discussion” within the party, and a rethink on policy-making to involve “as many members as possible”.

The SNP’s policy-making is notoriously closed and centralised, with the leadership writing the manifesto with negligible input from grassroots members.

Sheppard, a former Labour councillor and official who only joined the SNP in 2014, tried to make a virtue of his shallow roots in the party, by saying he was “fairly typical” of many of its new members and could bring “a new perspective to our leadership team”.

In a fresh development last night, Sheppard tried to head off accusations of a party split by insisting he was not trying to topple Robertson as SNP Westminster leader.

In a leaked letter to his fellow SNP MPs, he said his candidacy was “in no way a challenge to his leadership of our group here at Westminster which has been exemplary”.

Sheppard, founder of the Stand comedy clubs, went on: “Our group leader is part of the leadership team and he has my full support and confidence.”

Sheppard’s letter also said he wanted to get the SNP “ready to lead the Yes campaign and win independence for our country”.

At the last deputy leadership contest, in 2014, Hosie saw off challenges from MSPs Keith Brown and Angela Constance.

The all-male line-up this time is awkward for Sturgeon, who has a gender-balanced cabinet.

However Ochil and South Perthshire MP Tasmina Ahmed-Sheikh may yet enter the contest.

Nominations close on August 5 and the winner will be announced at SNP conference in October.