They are two of the most powerful women in British politics who could hold the balance of power after the General Election - and personal friends who regularly exchange text messages.

Plaid Cymru leader Leanne Wood and her Nationalist ally, First Minster Nicola Sturgeon, are likely to play a pivotal role in coalition talks if there's a hung parliament.

Wood's party holds three Westminster seats in Wales and she aiming to double that tally on May 5.

Meanwhile, polling suggests Sturgeon's SNP is on course to return as many as fifty Scottish MPs.

In an exclusive interview with The Sunday Herald, Wood has now paved the way for a formal pact with the SNP which could push Labour to agree to more powers for both Scotland and Wales.

The Welsh Assembly Member said: "Clearly the extra powers question is something that both the SNP and Plaid Cymru are keen to make sure is part of the agenda and it's something we can work together on.

"I think we'll work as a team and try to make sure that we get the best people in the negotiating team and we get the best programme to try and maximise the benefits.

"I'll be involved somehow. I haven't quite worked out exactly how it will work yet but I will be involved.

"I would imagine Nicola will have a strong role, even if she's not physically in the meetings. Clearly she's the leader and she'll have a strong influence on what happens."

Wood, 43, and Sturgeon, 44, both have working class roots and joined their respective Nationalist parties as young women.

They have developed a strong bond which will serve them well in the pressure cooker of coalition talks.

Wood said: "We message each other fairly regularly and speak and meet, of course.

"I was up at the SNP conference in November and had a fantastic time then - I was given a great welcome - and we had a formal meeting just before Christmas with the leaders of the Greens.

"There will be more meetings ahead of May 5. I'm coming up to Scotland at some point for a women leaders' debate. I'm sure we'll hook up then.

"I admire Nicola. I think she's achieved a great amount, particularly in the work she did in the referendum campaign. The strength with which she put forward the argument for a yes vote, certainly I think she's a very good politician."

Wood might well marvel at the First Minister who has been instrumental in growing support for Scottish independence to 45% of those who voted in last year's referendum.

Recent polling by ICM and the BBC put backing for Welsh independence as low as 3%, but Wood remains bullish.

She said: "There's a note of caution over that poll. It was a multiple choice question so there were five possible answers and 3% came out for the one that was independence."

The same poll suggested that around 50% would support more powers for the National Assembly of Wales.

"In terms of taxation powers, powers over energy, over criminal justice - these are powers we don't have yet in Wales - there is a majority support for those," said Wood, who has been an AM since 2003.

"My hunch is that people are moving in the direction of greater self-determination but our economic problems are deep and unless we can demonstrate to people that we are on course to be able to close the fiscal gap that exists in Wales I think winning a referendum on independence would be a big challenge.

"That's why all effort and priority has to go into turning around the Welsh economy and closing the fiscal gap so that we can demonstrate to people that we can not only stand on our own two feet but can thrive as an independent nation."

In the short term, Wood hopes to increase the number of Plaid Cymru MPs at Westminster from three to six.

She said: "We're actually hoping to have our best ever result at a UK General Election. There are six seats that we could win but I'm nervous about making predictions because it's a fool's game.

"We're focused at the moment on maximising the number of MPs. All our effort is going into that because our position in the event of a hung parliament is going to be dependent on the number of seats our parties have."

With both the Conservatives and Labour predicted to fall short of an overall majority, six Plaid Cymru seats will offer Wood some leverage, particularly if the party enters into a formal agreement with the SNP.

She said: "The time for working out the details of the more formal co-operation will come after the election. I wouldn't rule out a formal agreement (with the SNP) before the election but there are no plans in place at the moment to do that."

One thing Wood has ruled out is a coalition with Labour or the Conservatives.

She said: "A formal coalition (with Labour) would be unlikely but on a case by case basis we hope to win gains for Wales in particular votes.

"My view is that the Conservatives are to be ruled out because Wales has never voted for a Conservative government despite being harmed by a number of different Conservative governments.

"They are also ideologically committed to austerity so the possibility of trying to get them to change course is a lot more difficult than trying to persuade Labour.

"My view is there are still good members in the Labour Party, despite the leadership, and the fact that the relationship is still there with the unions, albeit to a lesser extent than it used to be, means that there are people we can work with in order to try to change the Labour Party's attitude to the whole austerity and cuts agenda. That's got to be what we have to try to do, I think."

In a speech in London this week Nicola Sturgeon attacked austerity and spoke of her desire for a "progressive alternative".

Leanne Wood's Plaid Cymru is very much part of that agenda.

"We're working with the SNP, and the Greens in England, to forward the alternative to austerity," said Wood.

"I've obviously got a good relationship with the First Minister. I've known her for many years.

"We are in contact regularly and clearly there is a lot of common ground between the two parties, particularly on the questions of powers and devolution and anti-austerity and Trident.

"This election is a great opportunity for both of our countries to make sure that Westminster takes note of the needs in our countries in the way they haven't done before.

"I think people in both our nations would be wise to grasp that opportunity with both hands. It's the best chance."