BUENOS AIRES, Oct 25 (Reuters) - Ruling party candidate Daniel Scioli called on the support of undecided voters after Sunday's first-round presidential election, though he stopped short of acknowledging that would have to face a run-off vote next month.

"I call upon the undecided and independent voters to join this cause," Scioli told thousands of party loyalists in the capital Buenos Aires.

(Reporitng by Hugh Bronstein; writing by Richard Lough; Editing by Christian Plumb)