The Commission on Civil Society and Democratic Engagement has called for the constituency spending limits for non-party campaigning contained in the lobbying bill to be removed.
The commission, a coalition of charities, campaign groups and academics set up to consider issues relating to the bill, today published its second report on the Transparency in Lobbying, Non-Party Campaigning and Trade Union Administration Bill.
It contains a number of recommendations relating to Part 2 of the bill, which will be debated in the House of Lords on Monday and is the section of most concern to charities.
The commission’s report says one of the most harmful parts of the bill is that charities and campaigners would be subject to a constituency limit on their campaign spending of £9,750, and recommends that it should be removed. The limit on total spending on campaigns "reasonably regarded as intended" to favour parties or candidates would be reduced from £988,500 to £390,000.
In its first report, the commission opposed limits because they were unworkable in practice, they would be disproportionate in curbing campaigning activity and they would pose a disproportionate administrative and legal burden. The Electoral Commission has since said the constituency controls "may be unenforceable within the timescales of an election", the second report says.
Other recommendations in the report include increasing the spending thresholds at which charities must register with the Electoral Commission from the proposed £10,000 in England to £20,000 and from £2,000 in Wales, Scotland and Northern Ireland to £10,000.
It also calls for the period during which non-party campaigners are regulated before elections to be reduced from the proposed one year to six months.
The commission, which is chaired by the former Bishop of Oxford, Lord Harries, said it has consulted with organisations around the UK to produce its recommendations.
The report also recommends that a parliamentary committee, such as the Political and Constitutional Reform Select Committee, reviews regulation of non-party campaigning after the 2015 general election.
The commission said the report would be launched with a "day of action" today in Westminster for its members to "air their anger" at the bill.
Sir Stephen Bubb, chief executive of the chief executives body Acevo, which helped set up the commission, said: "The lobbying bill still misses the fundamental purpose it set out to achieve: to increase the public's trust in politics. It gags charities and other campaigners while giving corporate lobbyists the run of Westminster. I welcome the commission’s report and urge government to listen."
The commission’s report includes a number of case studies of campaigns that would be affected by the legislation, including Stop HS2, Hope not Hate and Save Lewisham Hospital.
Bubb said: "This deeply flawed bill represents an assault on all campaigning groups; left or right, who do so much to bring our democracy to life. Its potential to gag grass-roots HS2 campaigners is another example of the damage it could cause to free and equal debate.
"The government must rethink – unless we want to become a beacon to oppressive regimes across the world, who want to gag their civil society."
Sir Stuart Etherington, chief executive of National Council for Voluntary Organisations, said: "Today’s report makes a helpful contribution. I am pleased to see the commission largely agree with our proposals for amendments. We will continue our constructive conversations with government over the coming weeks."
A Cabinet Office spokesman said: "We have provided extra time before the House of Lords debates Part 2 of the bill to allow for further discussion and consultation with campaigning groups, and we will be listening carefully to the views expressed in the Lords next week. The government has already indicated that we will be reconsidering the thresholds for registration with the Electoral Commission
"This report is another welcome addition to the debate, and we are pleased that the commission has endorsed our principle that third parties who campaign at elections should be subject to regulation.
"It would be premature to respond on any specific recommendations before the period of discussion has finished and before we have had the opportunity to hear the views of parliamentarians."