The Liberal Democrats are investigating allegations that two members of Norman Lamb's leadership campaign team breached party rules.
A formal disciplinary process has also started against the pair in connection with the claims.
It is understood Lib Dem officials will hold a formal discussion with the party's data controller tomorrow morning about the potential referral of the allegations to the Information Commissioner.
It has been reported the allegations centre on the potential use of party membership lists to conduct negative polling against Mr Lamb's leadership contender Tim Farron.
Mr Lamb told the Sunday Telegraph he had suspended the two individuals from further involvement with his campaign.
The North Norfolk MP and Mr Farron are the only candidates to have been nominated to succeed Nick Clegg as leader following a bruising general election campaign, which saw the party secure eight seats compared to 57 in 2010.
The winner of the ballot of party members is due to be announced on July 16.
A Liberal Democrat spokesman said: "We have been made aware of an alleged breach of party rules and are looking into the issue as a matter of urgency.
"The Liberal Democrats take any alleged breaches of party rules extremely seriously. The party has contacted both teams to reiterate rules on the leadership process."