WPP is seeking the consent of the Takeover Panel to invoke the material adverse change condition in relation to the deal. It is arguing that the situation has significantly worsened since the events of September 11.
It is seen as unlikely that the Takeover Panel will accept WPP's argument, which is likely to centre on the tumbling value of advertising and media stocks.
However, for the argument to be successful the Takeover Panel will have to see evidence that profits are set to dive at Tempus by at least 20%. Analysts are suggesting that Tempus may be down by only 10%.
At the weekend, it emerged that shareholders in Tempus have threatened WPP with legal action if it attempts to abandon the £432m bid to buy the company.
WPP has already asked to see Tempus's books, but Chris Ingram, the Tempus CEO, has refused to hand over the information. Tempus may, however, hand this data to the Takeover Panel to help it make its decision.
The use of the material adverse change clause by WPP is likely to be weakened by its purchase of a further 3% of Tempus stock after September 11. This raised its stake in Tempus from the 22% it bought earlier this year to 26%.
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