The State Department on Wednesday said it believes there are roughly 1,500 U.S. citizens left in Afghanistan who may wish to leave the country before an expected Friday deadline.

U.S. officials are in “direct contact” with approximately 500 of those Americans seeking evacuation and have provided them with “specific instructions on how to get to the airport safely,” Secretary of State Antony J. Blinken said during a Foggy Bottom press briefing.

As for the remaining 1,000 U.S. passport holders, Blinken said, “we are aggressively reaching out to them multiple times a day, through multiple forms of communication … to determine whether they still want to leave and to get [them] the most up-to-date instructions on how to do so.”

Of that estimated group of 1,000, the secretary said some may in fact not be Americans, others may have made their way out of the country without updating U.S. embassy officials and some may have decided to stay in the country.

“These are dynamic calculations that we are working hour-by-hour to refine for accuracy,” Blinken said.

The secretary said the 1,500 number does not include U.S. green card holders.

Since Aug. 14, more than 82,000 people have been flown out of Afghanistan, Blinken said, including approximately 19,000 people who left in the last 24 hours on U.S. military and coalition flights.

Those numbers include at least 4,500 U.S. citizens — including 500 flown to safety in the last day, he said.

While reiterating that President Joe Biden has requested contingency plans in case the Aug. 31 evacuation deadline needs to be postponed, Blinken gave little indication at the briefing that was something the administration is leaning toward. (At a news briefing shortly after he spoke, White House Press Secretary Jen Psaki told reporters Pentagon officials had briefed Biden on those plans earlier in the day.)

A significant number of GOP and Democratic lawmakers, many of them veterans of the Iraq and Afghanistan conflicts, and other former nationals security professionals have called on the administration to push back the deadline.

“It is not going to be possible to get American citizens out and our Afghan partners and their families out between now [and] the end of the month,” Rep. Jason Crow, D-Colo., a retired Army Ranger who served in Afghanistan and now sits on the Armed Services and Intelligence committees, told MSNBC on Tuesday. “The end of this mission should come not based on a calendar date. It should come when we accomplish the mission.”

While the official deadline for U.S. military evacuation efforts in Kabul is Aug. 31, in reality, the cut-off, as it has been conveyed to aid agencies, for evacuating civilians is Friday, Aug. 27. The military will need the remaining days to evacuate its 6,000 troops, many of them Marines who have been conducting evacuation operations at Hamid Karzai International Airport in Kabul.

“Extending it would certainly be ill-advised and probably would do more harm than good in the long run,” retired Marine Gen. James Cartwright, a former vice chairman of the Joint Chiefs of Staff during the Obama administration, said at an Atlantic Council online forum Wednesday.

“We don’t control approaches to the cities, we don’t control the countryside,” he said. “In order to do any kind of establishing order and reducing the chaos and allowing some sort of humanitarian airlift out of there or across the borders … will cost a lot of lives if we want to do that, and it will only prolong the outcome.”

Rather than focus on pushing for an extension of the deadline, Cartwright, who has backed a U.S. military drawdown in Afghanistan for years, argued the focus of the broader international community should be on developing plans for how to house and feed the thousands of Afghans who have fled the country and may likely grow into the millions over the coming weeks, months and years.

While some countries like Qatar and Uganda have agreed to accept small numbers of Afghan refugees, it is only on a temporary basis. Semi-permanent refugee camps would need to be created in third-party countries where Afghans can live safely while permanent living arrangements are worked out.

Afghan refugee camps will likely be needed for at least five to ten years, Cartwright said.

“In all, more than two dozen countries on four continents are contributing to the effort to transit, temporarily house or resettle those who we are evacuating,” Blinken said.

The secretary told reporters that just because the U.S. military presence was ending in Afghanistan on Aug. 31, it did not mean the State Department would cease its efforts to help U.S. citizens and vulnerable Afghans leave the country, particularly those who have worked for the U.S. government.

“The Taliban have made public and private commitments to provide safe passage past Aug. 31 for U.S. citizens, third-party nationals and vulnerable Afghans,” Blinken said, adding that the State Department was “developing detailed plans” to allow it to continue to provide some form of consular support past the end of the month.

Blinken said he would “use every diplomatic, economic, political, assistance tool at my disposal” to convince the Taliban to allow continued evacuations after the U.S. military has left.