The Artemis III Mission May Be Delayed Until Late 2027

In the first half of April, the Artemis II mission successfully concluded, bringing astronauts near the Moon for the first time since the Apollo program ended in 1972. NASA is now evaluating all the data gathered and the information collected by the crew to understand how to proceed with the space program aimed at establishing a permanent lunar base in the coming years, with a lunar landing expected in 2028. Recently, Jared Isaacman (NASA's administrator) announced a new change to the agency's plans.

NASA Might Delay Artemis III Until Late 2027
During a U.S. congressional hearing regarding the budget request from NASA, Isaacman stated that he had discussed with Blue Origin and SpaceX and received assurances that the lunar landers (Starship HLS and Blue Moon MK2) would be ready by the end of 2027 for the Artemis III mission.
It's noteworthy that, compared to previous announcements, NASA intends to conduct Artemis III as a low Earth orbit (LEO) mission and not as the mission that will return a crew to the lunar surface (similar to what happened with Apollo 9). The first mission that will include a crewed lunar landing for this program is now expected with Artemis IV in early 2028 and Artemis V at the end of 2028.

Only a short time ago, it had been announced that Artemis III would take place by mid-next year, and a delay of several months until late 2027 could also mean postponing the crewed lunar landing with Artemis IV to no earlier than mid-2028 or toward the end of the same year (but there could be further delays).
It must be noted that even if the Artemis III mission is entirely successful, allowing the two lunar landers to be tested in space, NASA has explicitly requested a test landing (without crew) to be performed before Artemis IV. This operation will still take time, and it is likely that a crewed lunar landing will happen approximately a year (or more) after the third mission of the program.

The timelines are tight, and China is quickly moving forward to complete key tests for its lunar program, which could culminate in a lunar landing in 2029 (or no later than 2030).
Artemis III could then "collide" with an unwritten rule called "Berger's Law" (coined by journalist Eric Berger of ArsTechnica) which suggests that a mission scheduled for the end of a year will inevitably slip to the following year.

Preparations for the Artemis III mission are still ongoing. The hardware intended for NASA's Space Launch System (SLS) and the Orion capsule is arriving at the Kennedy Space Center for assembly. The main stage, or core stage, of the Space Launch System was shipped from the Michoud Assembly Facility to Florida via barge and has been delivered to High Bay 2 of the Vehicle Assembly Building (VAB). Being an LEO mission, there will be no need for the ICPS upper stage, which could be replaced by a mockup for mechanical reasons or another solution that will be announced in the coming months.

Meanwhile, SpaceX is continuing tests for the twelfth launch of Starship (Flight 12), the first with third-generation hardware. At the same time, Blue Origin is developing its own solutions. This year, a demonstration mission for Blue Moon MK1 (a cargo lunar lander) that uses some technologies from Blue Moon MK2 (crewed lunar lander) will be launched. If Bezos's company succeeds, it may hope to surpass SpaceX to be employed during Artemis IV, but there are still many uncertainties. The spacesuits for extravehicular activities (AxEMU) would also be delayed, but Axiom Space has assured that they will be ready for testing next year, which could take place during Artemis III or aboard the ISS.