Jackie Ballard is standing for the Liberal Democrat leadership. Not that she can say so herself - or at least not yet. All the potential contenders to succeed Paddy Ashdown are abiding by a vow of public silence on the contest until the European elections on 10 June are safely out of the way. But stand Ballard will, her supporters make clear.

Asked directly, Ballard hides behind the agreed formula. "No-one is going to announce their candidacy until June the 11th, the day after the European elections," she says grinning widely, "because it's important that we focus on those elections."

Paddy Ashdown announced he was standing down as Lib Dem leader at the start of this year

So what's in her diary for 11 June? "Oh, I don't know what my diary says for 11 June," she says, entirely unconvincingly. She flamboyantly produces her diary from her handbag and turns, with a flourish, to the relevant page. Ballard will be in her Taunton constituency that day.

"And if I was to announce and launch a campaign, I would certainly do it in my constituency."

'My leadership style'

While she can't talk about running to be leader, surely there is nothing to stop her describing what a hypothetical Ballard leadership would be like?

"I don't even have to say it hypothetically," she says, reciting some of her pre-Westminster political experience. Ballard was deputy leader of South Somerset District Council for three years, its leader for one. She was also deputy leader of the county council for two years.

"So I've had experience of leadership. And in both those cases the groups had over 40 councillors in them - so they were similar-sized to the parliamentary party, in fact," she laughs.

Charles Kennedy is so far the favourite to succeed Ashdown

She also sits on the Lib Dems' federal executive, and before entering the Commons served on its federal policy committee for five years. She is now the Lib Dems' spokesperson on women and local government.

"My style of leadership was very inclusive," she says of her time in local government. "I don't believe that all the wisdom and work comes from the leader. I think that a hallmark of good leadership is your ability to involve other people, and your ability to trust other people."

Her former council colleagues in Somerset have, she says, been strongly urging her to stand. "And you could ask any of them what kind of leader I was. And I think they would say I was someone that was full of ideas, because I'm a thinker.

"I have got very clear ideas about how the party should develop and what we should be doing in policy terms - and it's in areas to do with injustice and poverty, and it's also in areas of style and devolution of power.

"And they would also say that I'm someone who involves other people. I'm not a one-woman band, I'm good at building teams around me."

That last bit can be taken as a coded criticism of Cap'n Paddy's dam-busting style. It's no secret that Ballard is one of the Lib Dem MPs that were not best pleased by some of his unilateral moves closer to New Labour recently. She promises a more collegiate approach.

Jackie Ballard shares the discontent of Lib Dem activists at Paddy Ashdown's closeness to Tony Blair

"The leader has to take the rest of the team with them," she says. "You have to take them into your confidence, you have to tell them where you would like to go. But at the end of the day if they're not following you, there's no point in leading."

Fear for Blair's PR promise

In the wake of the Scottish and Welsh elections, many electoral reformers suspect the results - dominance but not overall majorities for Labour in both devolved assemblies - may have hardened Tony Blair's reluctance to make progress on implementing proportional representation (PR) for Westminster. Ballard agrees: "I think that is a real danger, yes.

"We don't know what Blair's position on PR for Westminster is because he's not been terribly forthcoming about it. He's certainly not a great enthusiast for it, or else the Jenkins Report wouldn't have been kicked into touch, which it appears to have been," she says.

"I've always thought that at his heart Blair is not a pluralist. I think he would rather have a cosy relationship with the Liberal Democrats being sucked into how power structure than he would a genuine partnership between equals."

Ballard will, in the language of her party's coming leadership battle, be the "radical" candidate for the Lib Dem top job. She hails from that section of the party that has found the Lib-Labbery of recent years uncomfortable, if not downright unwise.

Tony Blair: Not a pluralist, according to Jackie Ballard

One of her backers in the as-yet unofficial contest is Conrad Russell, the Lib Dem peer who is one of the party's standard-bearers against cosying up to New Labour.

Ballard says the "constructive opposition" forged by Paddy Ashdown, should be allowed to continue for the duration of this parliament, so long as the remit of the joint cabinet committee on constitutional affairs, which includes a handful of Lib Dem MPs, is not expanded.

'Exit strategy' required

"Well, there are still issues on the constitutional agenda to be dealt with, not least PR for UK elections and local government, not least freedom of information and House of Lords reform," Ballard says. But these areas of co-operation, she insists, must be fully concluded before any others are taken on.

So clear progress on the key constitutional reform issues - especially the question of Labour's promised referendum on PR for Westminster - should be forthcoming over this year, or the Lib Dems should think about disbanding the joint committee? "Yes," is Ballard's firm answer.

"If the process has stalled completely then there is no point in just sitting on a joint cabinet committee that meets once a month and is not achieving anything, because there are dangers in sitting on it in the first place for us," she warns.

Simon Hughes: The Southwark MP is another likely leadership contender Jackie Ballard will have to beat

Chief among those dangers is co-option to little effect in terms of government action, the accusation from other parties that a vote for the Lib Dems is a vote for Labour, and taint by association once the government, as all governments eventually do, becomes unpopular.

While progress in certain reform areas has been made, "there may come a point where, if progress is not made on those outstanding constitutional issues, the price that we're paying for being in it [the joint cabinet committee] is too high. Then we have to have a clear exit strategy."

Referendum legislation demand

Ballard sets out a specific benchmark for progress. Last November she helped through the Lib Dem federal executive an amendment stipulating that no further extension to the JCC's remit should happen unless the next Queen's Speech contained enabling legislation for the PR referendum.

Her intention was "not to insist there must be a referendum in this parliament," she explains, "but to enable it to happen if people thought it was the right thing to do". Whether the government announces the legislation in this autumn's Queen's Speech is "a pretty clear test".

She does not accept other pro-PR campaigners' resignation that a referendum is off the cards until after the next election, despite Labour's manifesto promise.

Lord Jenkins of Hillhead: The Lib Dem peer's report on PR is gathering dust on a Downing Street shelf

"This has to be a two-way street," she says of the co-operation of the two parties which led to last year's Jenkins Report recommending PR for the Commons. The prime minister had asked the Lib Dem peer to examine the subject. His final conclusions have been gathering dust ever since.

"How long is that report going to sit on the shelf before people decide that you may as well put it in the bin?" Ballard wonders. "If the enabling legislation isn't in the Queen's Speech it will have sat on the shelf for a year." Its non-appearance, she says, would be unacceptable.

Popular at the grassroots

In the four months since Ashdown stunned Westminster by announcing he was to step down as leader, Ballard has come from being seen as a no-hope outsider - some commentators wrote of her as merely a possible "token woman" candidate - to serious contender.

The initial underestimation was initially due to the assumption from Westminster-watchers that because she only arrived in the Commons at the last election, she was a political novice.

As well as her local government record, however, she is a proven popular figure with grassroots Lib Dems. When she won her place on the federal executive she topped the ballot - ahead of Charles Kennedy, among others.

"It may surprise the media in Westminster that someone who's only been in Parliament for two years can be talked about seriously as a potential leadership contender," Ballard says.

"But it wouldn't surprise the 5,000 Liberal Democrat councillors across the country, or lots and lots of activists who heard of me long before I was in Parliament."