Bill Ackman's Pershing Square does not have the votes to win three seats on ADP's board at the company's annual meeting Tuesday, according to multiple investors.
Responding to CNBC's report, Ackman said on "Fast Money Halftime Report" on Monday, "The facts are, I don't know if we're going to win or lose tomorrow; neither does ADP."
"I don't think there's any way [that] any one today could call the election," added Ackman.
The activist hedge fund manager owns an 8 percent stake in the payroll processor and is waging a proxy fight that has grown heated at times as the two sides battled it out publicly. Ackman's effort to secure board seats recently got backing from proxy advisory firms.
Shares of ADP fell 1 percent in early trading on Monday.
Ackman revealed his stake in ADP in August and said the company could boost returns by streamlining operations. The company has dismissed his claims as "false and reckless."
It hasn't been a good few months for activist investors, however. Fellow hedge fund manager David Einhorn failed in his bid to get on the board of General Motors in June, and Trian Partner's Nelson Peltz lost a very close proxy war to get on the board of Procter & Gamble last month.