WASHINGTON: The final days of the high-stakes Iranian nuclear negotiations have been filled with a flurry of diplomatic wrangling and marathon meetings in Vienna.

But back at the White House, the quest to fulfill one of President Barack Obama's top foreign policy priorities can seem more like a waiting game.

The deadline-busting talks have put Obama's public appearances largely on hold while negotiators wrestle with the details of a deal to curb Iran's nuclear program in exchange for international sanctions relief. Rather than risk having to rip up carefully crafted schedules if a deal comes together, advisers are leaving Obama available to jumpstart a robust sales pitch at home and abroad if negotiators reach an agreement.

"The president's schedule has been left intentionally fluid to account for the fact that we may have news out of Vienna," White House spokesman Josh Earnest said.

The US and its negotiating partners — Britain, France, Germany, Russia and China — have already blown through a June 30 deadline for reaching a final accord. With a new deadline Friday, Secretary of State John Kerry suggested that it, too, could fall by the wayside.

"We will not rush and we will not be rushed," Kerry said.

Obama has ceded the actual negotiating to Kerry and Energy Secretary Ernest Moniz, a nuclear physicist who has been hammering out technical details with his Iranian counterparts.

The Cabinet secretaries and other U.S. negotiators have spent the last two weeks cloistered in the Austrian capital, fueled not only by their desire to reach an elusive nuclear accord, but also an impressive supply of snacks: 10 pounds of Twizzlers, 20 pounds of string cheese, 30 pounds of mixed nuts and dried fruit, and more than 200 Rice Krispies treats.

Officials say the negotiators in Vienna and officials in Washington are in near-constant communication. Kerry speaks regularly to national security adviser Susan Rice, who in turn briefs Obama. Technical teams in Washington and Vienna also speak frequently, as do communications aides trying to coordinate their public statements.

While Obama isn't at the negotiating table himself, officials say he has become steeped in the intricate details of Iran's nuclear program and frequently asks technical questions.

On Wednesday, the president convened a 90-minute video conference in the Situation Room with Kerry, Moniz and other negotiators. The White House closely guarded details of the discussion, saying only that the president provided the team with unspecified "guidance."

The only hint at Obama's mindset as another deadline nears came from Democratic lawmakers who attended a private meeting with him earlier in the week. According to those in attendance, the president put the prospects of finalizing a legacy-defining nuclear as a 50-50 proposition at best.