David Cameron has been accused of mounting a "shabby" partisan attack on the Labour Party in the wake of the recent lobbying scandals after Downing Street swiftly announced new laws that appear to target trade unions.
A bill to create a statutory register of lobbyists is to be brought in before parliament breaks for its summer recess next month, No.10 announced on Monday afternoon.
The announcement comes in the wake of a rash of lobbying scandals, which saw a Conservative MP and an Ulster Unionist peer resigning the party whip and two Labour peers suspended after it was alleged that they breached parliamentary rules.
Under the new proposals, unions will be required to carry out an annual audit of their membership and demonstrate that the figures they produce are accurate. The Certification Officer will be given the power to conduct investigations into the numbers produced, which are vital when ballots on strike action are conducted.
And unions appear to be the main target of the proposed changes to third-party election campaign funding, which will apply to organisations affiliated to political parties as those making major donations of more than £100,000.
The reforms will ensure that the true value of activities such as leaflet-printing is reflected when judging whether parties have breached the £19 million cap on campaign spending in the year before a general election, said No 10.
When calculating the campaign spending they must declare, organisations such as unions would have to include not only the cost of printing a leaflet but also overheads such as staffing and rent on premises - which could potentially inflate the figure considerably.
The Labour Party has attacked the move as a "shabby and panicked response by David Cameron to divert attention from a set of damaging headlines hitting the Conservative Party".
And Tom Brake, the Lib Dem minister in charge of lobbying reform, suggested that the measures relating to unions and third-party funding may have been announced prematurely by Downing Street.
"The focus is very much on lobbying and any announcements that is made, I think, might be slightly premature in relation to other aspects of this," he said.
Before the last election, Cameron warned that lobbying would be the next big scandal to hit politics, and the idea of a register was included in the 2010 Coalition Agreement, but the Government was criticised for failing to include it in the Queen's Speech.
The House of Lords standards commissioner has begun investigating the three peers caught up in the latest lobbying scandal - ex-cabinet minister Lord Cunningham and Lord Mackenzie of Framwellgate, who have both been suspended by Labour, and Lord Laird, who has resigned from the Ulster Unionists.
The PM's spokesman said the government will table the lobbying Bill before the Commons rises for its summer recess on July 18 and intends to put it into law by the end of this parliamentary session in May next year.
Meanwhile, proposals to create a power for voters to recall MPs who misbehave will not feature in the government's legislative agenda until the final session of this parliament in 2014/15.