President Obama held a video meeting with Secretary of State John Kerry and other officials in Vienna late Wednesday, as part of his push to finish a deal to curtail Iran's nuclear ambitions ahead of a congressional deadline of midnight.

"This afternoon, the president and his national security team held a secure video conference with Secretary Kerry, [Energy] Secretary [Ernest] Moniz and the U.S. negotiating team in Vienna," the White House stated in a "readout" Wednesday evening. "The president reviewed the progress of negotiations to date, and provided guidance related to our ongoing efforts to achieve a good deal between the P5+1 and Iran that meets our requirements."

Obama's check-in could be a sign that his team is close to reaching some kind of agreement. Negotiation watchers liken the activity in the last 24 hours to that which led up to the April interim agreement, which laid out the framework for a deal and set a June 30 deadline.

That deadline has been exceeded, and officials have said they would talk until Friday. Officials haven't ruled out that it might be extended again if there's no deal by the end of Friday.

Kerry was expected to provide an update to the talks at 1 p.m. EST, from Vienna. A State Department official stressed that his remarks would be aimed at "updating" reporters on the state of the talks.

Congress' timetable might also factor into the talks. Reaching a deal by Thursday would mean Congress has 30 days to review the agreement. If more days or weeks are needed, that review period would be extended by another 30 days.

Kerry said early Thursday that his team is working to see what can be done.

"Continuing to discuss difficult issues this AM," Secretary of State John Kerry tweeted early Thursday morning. "Working diligently to see if agreement possible."