Mr. Obama’s comments came after a meeting with Secretary of State John Kerry, who had just finished three days of talks in Vienna with his Iranian counterpart. Mr. Kerry signaled in a brief news conference on Tuesday that he believed enough progress had been made to warrant an extension.

The negotiations are aimed at preventing Iran from developing a “threshold” nuclear capability that it could use to build a bomb. Mr. Kerry’s goal has been to ensure that Iran’s nuclear infrastructure remains at an early enough stage that it would take Tehran at least a year to produce a nuclear weapon should its leaders renege on any agreement.

Mr. Obama, who has been focused on his domestic economic agenda, also addressed other of what he called “pressing foreign policy challenges” during a less than eight-minute appearance in the White House briefing room, although the main topic was the new round of sanctions aimed at Russia.