The Scottish first minister, Alex Salmond, has hinted he could be open to a coalition between Labour and the Scottish National party (SNP), raising the possibility that he could return to Westminster and take a senior role in the government next May.

The SNP leader, who will be replaced by his deputy Nicola Sturgeon later this month, said he would make a decision soon about whether to run as an MP at the general election.

While ruling out a coalition with the Conservatives, he left the door open for a partnership with Labour. This could be a possibility if the SNP continues its strong showing in the polls and takes a large number of seats from Labour next year.

Speaking on the BBC’s Andrew Marr Show, he said: “I certainly think that there’s no chance whatsoever of the SNP ever going into coalition with the Conservative party, with their attitude towards Scotland, and their attitude towards people in general. I think it’s unlikely [with Labour] but who knows, people change sometimes, parties change sometimes, party leaders change sometimes and lead them in a different direction.”

He added: “It’s unlikely the SNP would see itself in a Westminster coalition. I’m fortunate because I am one of the few leaders, probably the only one that’s run a minority government. From that side … I have a very close understanding of what other parties should do to have the maximum influence on a minority government. There would be greater tractions on negotiating support on a case-by-case basis.”

If the SNP had enough seats to form a coalition with Labour and Salmond were an MP, there is a chance he could be given a senior role in the government like Nick Clegg, who became the Liberal Democrat deputy prime minister in 2010.

Salmond also said he still believed Scottish independence was the ultimate destination and the referendum lost by the yes campaign in September was just a stop along the way. Polls show surging support for the SNP at the moment, and one YouGov survey has found 52% of people were in favour of leaving the UK just weeks after the nation voted to stay in the union.

He made the comments against a backdrop of turmoil in Scottish Labour, whose leader Johann Lamont stepped down warning the party in Scotland was being run like a branch office from London.

Jim Murphy, the shadow development secretary, is the favourite to succeed her, but the biggest unions are backing MSP Neil Findlay. The third candidate is another MSP, Sarah Boyack.

Speaking on the Marr programme as well, Murphy said Sturgeon should be worried about Salmond trying to run the party from London if he gets elected next year.

“If I was Nicola Sturgeon I would be a bit worried that she’s going to have a backseat driver looking over and directing her from the House of Commons in that sense,” he said.

Murphy has said he would like to be in Holyrood by 2016 but there is not currently a vacancy and several MSPs who looked likely to retire are now keeping their seats.

Murphy quit Ed Miliband’s shadow cabinet on Sunday, telling BBC Radio 5’s Pienaar’s Politics that he wanted to concentrate on the campaign. Acknowledging he may have a job to convince the unions, he joked: “Getting on Len McCluskey’s good side? That’s a job for another day.”

One of the key issues for Murphy will be how to play the topic of devolution, as Labour is resisting the idea of giving Holyrood full powers over tax. Murphy said he believes Scotland should have more powers over tax, welfare and other social issues, but he stands by Labour’s central position.

He also said it was “slapdash and careless” of David Cameron to rush into constitutional issues such as English votes for English laws without considering them properly.