A Romney aide confirmed the call would take place between the two men, who held talks in Israel in July during a Romney visit, but did not provide details.

White House spokesman Jay Carney said Obama would likely have a phone conversation with Netanyahu on Friday, following up on the Israeli's meeting with US Secretary of State Hillary Clinton.

Netanyahu is likely to discuss his call for an international "red line" on Iran's nuclear program that he outlined Thursday at the UN General Assembly, where he brought out a cartoonish diagram of a bomb and drew a red line across it for emphasis.

Romney, who was attending a fundraiser in the northeastern city of Philadelphia early Thursday before addressing a nearby military academy, said the previous day that "I stand with Prime Minister Netanyahu."

He made the comment after the Israeli's UN address about the need to stop Tehran from enriching enough uranium for a nuclear bomb.

Obama, who was heavily criticized by Romney and other Republicans for not meeting with Netanyahu in New York this week on the sidelines of the United Nations gathering, has rejected the idea of an international red line on Iran.

But at the UN Tuesday, the president repeated his assertion that the United States will "do what we must to prevent Iran from obtaining a nuclear weapon."