The Government has been forced to make fresh concessions over its controversial Lobbying Bill in an attempt to head off a damaging defeat over new rules on campaign spending by charities.
Ministers will table a series of amendments to the Bill today easing the restrictions on how much charities and other non-party organisations can spend in the run-up to a general election, the Press Association has learned, amid claims they would have a "chilling" effect on their campaigning activities.
While campaigners have welcomed the changes, they warned that ministers still faced defeat when the Bill comes back to the House of Lords next week, unless there are further concessions.
Lord Harries of Pentregarth, the former bishop of Oxford, who chairs the Commission on Civil Society and Democratic Engagement - an umbrella group representing more than 100 non-government organisations - said there were still "major issues" to be resolved.
"I would like to congratulate all charities and campaigning organisations for bringing about a significant change of heart by Government," he said.
"Ministers have recognised the force of the arguments put to them and have made important concessions. However there are still some major issues that need to be resolved."
The main changes include dropping a plan to cut the amount charities in England can spend on campaigning during the "regulated" period before a general election before they have to register with the Electoral Commission from £5,000 to £10,000. Instead the limit will now be raised to £20,000.
For charities in Scotland, Wales and Northern Ireland, the threshold will rise from the current limit £5,000 to £10,000, rather than a planned cut to £2,000.
The Government has also conceded that for the next general election in May 2015, the regulated period for third parties - which is normally 12 months - will now start on September 19 2014, the day after the Scottish referendum.
The proposed overall spending limit for charities across the UK during the regulated period is also being raised from £390,000 to £450,000 - although campaigners say this is still a long way short of the existing cap of £988,500.
Details of the changes were outlined last night at a briefing for peers by the Cabinet Office Minister Greg Clark and the Liberal Democrat leader in the Lords, Lord Wallace of Tankerness.
The concessions come after ministers were forced to announce a six-week "pause" in the legislation in November in the face of growing opposition in the upper chamber.
Campaigners however remain concerned that the bill has widened the definition of campaign spending to cover staffing costs, and new limits on spending in individual constituencies and restrictions on charities and campaign groups working in coalition together.
Liz Hutchins of Friends of the Earth said: "Ministers have accepted that they have made serious mistakes with the Lobbying Bill and have backtracked on several issues.
"However the legislation would still impose significant new restrictions on charities and campaigning organisations from speaking out ahead of elections.
"The proposed inclusion of staff costs would mean significant additional red tape for charities that political parties do not face. Proposed new constituency limits remain unworkable and unenforceable. Charities and campaigning organisations are more effective working together yet this Bill makes this more difficult."
A Cabinet Office spokesman said that ministers had agreed to amend the legislation after listening to the concerns of charities and campaign groups.
"The measures in the Bill were never aimed at organisations who do not seek to influence the outcome of elections. We have listened to the debates in the House of Lords and held discussions with around 50 interested organisations in recent weeks. These amendments directly address the concerns raised while preserving the core purpose of the Bill," the spokesman said.
"In particular we will meet a key recommendation of the Harries commission to raise registration thresholds, effectively exempting smaller campaigning organisations and the vast majority of charities from regulation.
"Taken alongside the rest of the package, which includes a reduction in the regulated period for the 2015 election, it represents an important change to the Bill. The Government hopes that those who have been working so hard with us to get this Bill right will now support these changes so that we can introduce these important reforms."