Israeli Prime Minister Benjamin Netanyahu refused to endorse Mitt Romney's criticism of President Obama's policy toward Israel in an interview Sunday, and wouldn't wade into  the U.S. presidential race, saying that preventing Iran from obtaining a nuclear weapon "is really not a partisan issue."

In an interview on NBC's "Meet The Press," host David Gregory asked Netanyahu about Romney's claim that the Obama administration has thrown Israel "under the bus."

"There is no bus, and we are not going to get in to that discussion," Netanyahu said, before adding: "The only bus that is really important is the Iranian nuclear bus. That's the one that we have to derail."

Netanyahu underscored the urgency of preventing Iran from obtaining a nuclear weapon. "I think you have to place that red line before them now, before it's too late," he said. "They are in the red zone -- they are in the last 20 yards, and you can't let them cross that goal line."

Netanyahu added that he has no doubt that both Romney and Obama are committed to preventing Iran from obtaining a nuclear weapon.

Speaking on the same program, U.S. Ambassador to the United Nations Susan Rice defended the Obama administration's efforts to keep Iran from getting a nuclear weapon and reiterated the administration's commitment to that goal.

"Our bottom line -- if you want to call it a red line -- the president's bottom line has been that Iran will not acquire a nuclear weapon. And we will take no action off the table to ensure that it does not acquire a nuclear weapon," she said.