The boss of the world's biggest advertising company could become the sixth top chief executive this year to have their pay package rejected by investors as part of the so-called Shareholder Spring.
Sir Martin Sorrell, who founded WPP in 1985, has defended the 56% increase for 2011 as a reward for "performance, not failure".
But institutional investors appear set to deliver a non-binding vote against the total package, worth up to £13m, arguing it is out of sync with the return on their investments.
Shareholder advisory groups, including the Association of British Insurers (ABI) and Pensions Investment Research Consultants (Pirc), have urged members not to back the advertising group's remuneration report, claiming it is excessive.
They say this is purely about pay and not Sir Martin, who they hold in the highest regard.
He has said the deal is reflective of his performance since the group reported profits of £1bn for the first time in 2011.
Writing in the Financial Times last week, he issued a robust defence of his pay, warning that if Britain wanted high achievers in the private sector, it needed to pay competitively.
He told the paper: "The compensation debate in the UK now seems to have shifted from undeserving bankers paid for failure and from payment for performance to what is fair pay."
However, chairman Philip Lader, a former White House deputy chief of staff, took a more conciliatory approach and said all pay deals were open to further
The AGM in Dublin today follows months of shareholder ire over executive pay with the likes of Aviva, Trinity Mirror, Barclays, William Hill, Xstrata and Premier Foods all facing significant votes against their pay reports.
A report by proxy voting agency Manifest and remuneration consultancy MM&K yesterday revealed rewards for FTSE 100 company bosses rose 12% to an average of £4.8m last year.
The Business Secretary Vince Cable, who is currently drawing up plans to give greater power to shareholders, is understood to be considering watering down proposals for a binding annual vote in favour of a poll every three years.
It had been feared that a binding annual vote would make investors less inclined to protest in case they destabilised management teams and would add to