Theresa May will vow never to allow the UK to become "looser and weaker'' in a speech ahead of a meeting in Scotland with Nicola Sturgeon.
Carmichael In Devolution Talks Move
Political leaders will be invited to discuss further powers for Scotland within weeks of a No vote in the independence referendum, Scottish Secretary Alistair Carmichael has confirmed.
Mr Carmichael plans to host a "conference on the new Scotland'' involving all of the main Scottish parties to take forward the devolution agenda.
The details of such a meeting were first set out by his Liberal Democrat colleague Sir Menzies Campbell in his report laying out the route to a formal agreement on more powers for Holyrood.
He proposed that the Scottish Secretary should invite politicians to start that process not more than a month after the September 18 referendum.
Mr Carmichael is expected to build on the pledge when he speaks at the Scottish Engineering annual dinner in Glasgow on Thursday.
He is expected to say: "People are, of course, asking what will be the consequences of a No vote this September. They are right to ask.
"When people go to cast their ballot, they should understand the consequences of either outcome.''
He will add: "In the event of a No vote, change will come. Scotland will have more powers.
"Getting to that destination involves bringing together all of those who have engaged with this debate and produced ideas and contributions of their own.
"So that the ground can be cleared, consensus can be reached and action can be planned.
"If Scots vote to stay within the UK family, as I believe we will, only then can we ask those who wanted to leave to set aside their differences with us, work together and deliver a package of powers around which Scotland can unite.
"But people do need to know that the invitation will be put, and that regardless of whether the SNP accepts it, the process will move forward.
"Ming Campbell's report proposed the way that this should happen.
"It proposed that the Secretary of State for Scotland should convene a meeting of the Scottish parties - a conference on the new Scotland - not more than one month after September 18 to begin the process of working together on more powers for Holyrood.
"I accept that proposal.
"And I can confirm that in the event of a No vote, I will invite the representatives of Scotland's main parties to meet in October to begin that process.
"There will be a conference on the new Scotland. It will work in the interests of the people of this country. And more powers will come.''
Mr Carmichael's pledge comes after a visit from Deputy Prime Minister Nick Clegg to Edinburgh, during which he told business leaders that the Lib Dems are the "guarantors'' of more powers for Scotland.
The party wants Holyrood to raise half of its own revenue and set its own rates of income tax, capital gains tax and inheritance tax.
Labour has also set out plans for further devolution while the Tories' commission on more powers is expected to report back soon.
Any final settlement would have to be negotiated with the other pro-UK parties, businesses, and wider civic Scotland, Mr Clegg said.
SNP MSP Linda Fabiani said: "We are entirely focused on achieving a Yes vote in September in the best interests of Scotland - and are confident of doing so, with the polls showing Yes well within reach of success in September.
"The fact is that only a Yes vote can guarantee the powers Scotland needs to be a fairer, more prosperous country - the No parties have nothing substantial to offer Scotland. David Cameron has totally refused to confirm what, if any, powers might be devolved after a No vote. And as Professor John Curtice has said, Labour's Devolution Commission proposals 'fall well short' of the powers the majority of people in Scotland would like.
"Mr Carmichael's party have been promising Home Rule for over 100 years, yet as recently as 2011 the Lib Dems had the chance to beef up the Scotland Bill with a raft of new economic powers that they had previously supported - but they reneged on their previous commitments.
"Westminster's broken promises on the constitution are no doubt one reason why senior Lib Dems - such as Andy Myles and Denis Robertson Sullivan - have come to the conclusion that only a Yes vote can deliver the powers Scotland needs.''
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