NASA officials on Monday offered more details behind the decision to postpone the Artemis I launch.

Mike Sarafin, Artemis mission manager, explained engine three was not cooling down enough to the temperature needed before ignition.

"I don't recall exactly where the engines were but engines one, two and four were pretty close to that. Three was not getting there," he told reporters during a media briefing Monday afternoon.

Sarafin said there were other issues earlier in the day including tanking -- filling the rocket with liquid oxygen and liquid hydrogen -- being delayed for about an hour after the Kennedy Space Center went into a lightning alert as well as a hydrogen leak, although both were resolved.

"So the combination of not being able to get engine three to reach chill down and then the vent valve issue that they saw at the inner tank really caused us to pause today and we felt like we needed a little more time," he said.

Sarafin added that he is hopeful about the second launch opportunity on Sept. 2.

"There is a non-zero chance we have a launch opportunity on Friday," he said.

"But we need time, we really need time to look at all the all the information, all the data and, you know, we're gonna play all nine innings here and we're not ready to give up yet," Sarafin continued.

NASA Administrator Bill Nelson said it's normal for launches to be scrubbed after the Artemis I launch was delayed Monday for multiple reasons.

"I am very proud of this launch team. They have solved several problems along the way and they got to one that needed time to be solved," he told reporters.

"I want to say, understand that scrubs are just a part of this program on the space flight," Nelson said.

Nelson spoke about the seventh mission of Space Shuttle Columbia, which he flew in January 1986.

"We scrubbed four times on the pad," Nelson said.

He added, "It was the better part of a month and, looking back, after the fifth try got off to a perfect mission. It would have not been a good day had we launched on any one of those four scrubs. So when you're dealing in a high-risk business and spaceflight is risky, that's what you do."

Vice President Kamala Harris praised the NASA team behind the Artemis I mission after the launch had to be scrubbed Monday due to an engine problem.

Harris and second gentleman Doug Emhoff had been visiting the Kennedy Space Center before the launch was postponed.

The scrubbed launch was "about showing the great work that happens here," Harris told reporters.

"These exceptional public servants, these exceptional skilled professionals who have the ability to see what is possible and what has never been done before. How exciting is that?" she said.

According to a White House official, Harris and Emhoff will continue with their visit under a revised itinerary.

"She met with astronauts at NASA Operations Support Building II and will proceed to a tour of Artemis II and Artemis III hardware as planned. The Vice President will gaggle following the tour and then depart," the official said.

-ABC News' Benjamin Gittleson

NASA Administrator Bill Nelson defended the scrubbing of the Artemis I launch, saying the launch shouldn't take place until the team is sure it's ready.

"We don't launch until it's right," he said during an interview on NASA TV Monday morning.

"There are certain guidelines. And I think it's just illustrative that this is a very complicated machine, a very complicated system, and all those things have to work, and you don't want to light the candle until it's ready to go."

Nelson said the engineers will continue to "stress" and "test" the rocket to make sure it's ready by the next attempt, which is Sept. 2.

Earlier in the day, Nelson had welcomed several Biden administration officials, including Vice President Kamala Harris and second gentleman Doug Emhoff, to the Kennedy Space Center ahead of the launch.

He said the vice president has been briefed and the White House will continue to receive regular updates.