It would be fair to say the elections for the leadership of both the Labour Party and the Liberal Democrats have yet to capture the public imagination.

The Labour contests, both at Westminster and the equally important campaign to select a new Scottish Labour leader, have a while to run. But Nick Clegg's successor at the helm of the Liberal Democrats will be chosen on July 6th. Popular engagement with any of these selection processes is running only a little above zero.

It is perhaps understandable that the Liberals' contest has been low-key. The party was shattered by the defeat at the polls in May, and lost 86 per cent of its MPs so has been significantly depleted.

Norman Lamb, who is contesting the leadership with Tim Farron, believes the party's fortunes can be revived relatively readily, in what he sees as a new age of consumerist politics, where voters select parties according to current policies and concerns rather than past allegiances.

He is probably right about that, but equally, having so alienated consumers his party may risk becoming an irrelevance.

That would not be in anyone's interests. Neither is a Labour Party which remains as weak as it currently does either in Scotland, or in the UK at large.

Apart from the proposals from outgoing leader Jim Murphy, adopted by the party - including deciding the next leader on a one-member, one-vote basis and changing the system for deciding list MPs - there has been little to catch the imagination in the Scottish leadership race thus far. Meanwhile the two candidates have yet to really answer the crucial question of how they can make the Scottish party distinctive and less of a branch office to the London party - although there were suggestions yesterday that the creation of an English Labour Party is under consideration.

Both Labour's wipe-out in Scotland its catastrophic result in the rest of the UK were followed by promises of a re-evaluation of what the party stands for and the kind of change it wants to see. There has been limited evidence of this so far, with candidates appearing to scramble to demonstrate their ability to seize the centre ground.

The inclusion of Jeremy Corbyn on the ballot should help to ensure a broader debate in the weeks to come and his presence certainly livens up leadership debates as he takes traditional 'old Labour' positions on issues such as trident, austerity and immigration. His involvement makes most of his rivals look mealy mouthed, but it would be a surprise if Ed Miliband's defeat did not see the party rein in some of its more socialist instincts in favour of a candidate who will not scare middle England.

All of this matters because there is an urgent need, both at Holyrood and at Westminster for an effective opposition. In Scotland, opponents are needed to the dominant SNP, to challenge the party's record in government on issues such as the health service and education. Meanwhile at Westminster, the Conservatives' majority is small but they appear reinvigorated by David Cameron's unexpected election triumph. Nevertheless, they must remain answerable to the whole electorate, having won power despite gaining just 37 per cent of the popular vote.