Prosecutors are expected to announce on Wednesday whether Conservative politicians or officials will face criminal charges over alleged electoral expenses fraud, according to reports.
The Crown Prosecution Service (CPS) has been considering files submitted by 15 police forces across England in relation to activities surrounding Tory campaigning in the 2015 general election.
The investigation centres on allegations that expenses were incorrectly recorded, raising the potential for offences under the Representation of the People's Act 1983.
Decisions on whether to press charges had been expected to come in late May or early June, but reports on Wednesday suggested an announcement was imminent.
Allegations highlighted by Channel 4 News and the Daily Mirror relate to busloads of Conservative activists sent to key seats, whose expenses were reported as part of national campaign spending rather than falling within the lower constituency limits.
The precise deadlines for charging decisions vary from area to area, depending on the date last year on which the local force secured an extension to its investigations into alleged breaches of election finance laws.
In April Scottish First Minister Nicola Sturgeon suggested that Prime Minister Theresa May called a snap election before the probe "catches up with her".
The CPS said the June 8 poll would have no impact on the timing of decisions on whether to press charges.
Each file relates to allegations concerning a candidate and an election agent and the number of people involved totals at least 30.
The CPS has received files from the following police forces: Avon & Somerset, Cumbria, Derbyshire, Devon & Cornwall, Gloucestershire, Greater Manchester, Kent, Lincolnshire, Metropolitan, Northamptonshire, Nottinghamshire, Staffordshire, West Mercia, West Midlands, West Yorkshire.
Kent Police have been investigating the Conservatives' spending return for the South Thanet constituency, where Craig Mackinlay beat former Ukip leader Nigel Farage by more than 2,000 votes in a hard-fought 2015 campaign.
In a statement last month, Mr Mackinlay, who has been interviewed under caution as part of the inquiry, said: "I have done nothing wrong and acted honestly and properly throughout."
In March the Conservative Party was fined a record £70,000 by the Electoral Commission for "numerous failures" in reporting its expenses for the 2015 General Election, and three by-elections in 2014.
Commission chairman Sir John Holmes said the Tories' failure to follow the rules "undermined voters' confidence in our democratic processes" and said there was a risk political parties were seeing such fines as "a cost of doing business".
The Conservatives accepted the fine but their claim that they complied fully with the investigation was questioned by the Commission, which revealed it had to go to court to obtain certain information from the party and criticised its "unreasonable uncooperative conduct".
A Conservative Party spokesman said at the time: "Political parties of all colours have made reporting mistakes from time to time.
"The Labour Party and Liberal Democrats both failed to declare sums of money which constituted a larger proportion of their national expenditure in the 2015 general election.
"Both have been fined by the Electoral Commission, and the Liberal Democrats are also under police investigation.
"This is the first time the Conservative Party has been fined for a reporting error."