In the moments immediately after state officials released New York City’s test scores on Wednesday morning, Mayor Bill de Blasio seized on the apparent gains — six points in reading and five points in math — as evidence that his education agenda is bearing fruit.

“We now have a school system that is steadily improving before our eyes,” he said in a statement.

But hours later at a press conference at P.S. 204 in the Bronx — and after state officials repeatedly stressed that the scores are not comparable to last year because of changes in the length of the tests — de Blasio chalked up the initial “over exuberance” to his aides, who he suggested had written the statement on his behalf.

Still, de Blasio said the next two years of testing, which are not expected to be marred by changes to the state reading and math exams, will offer a better window into the school system’s overall health.

“This now gives us a baseline to work from in the years ahead,” de Blasio said. “It is a reset moment in a lot of ways.”

With that baseline are likely to come new political pressures. Next year will be the first time students who came up through de Blasio’s universal pre-K program will have taken state tests. That push for expanded early childhood programs has been heralded as one of the mayor’s signature education accomplishments, and hard data could cement that part of his education legacy —  or it could raise questions about whether it’s working as expected.

More consistent data will also create pressure on schools Chancellor Richard Carranza who has vowed to tackle some of the school system’s most glaring inequities, most notably school segregation. On Wednesday, he said the gaps between different racial groups in reading and math are “unacceptable” — ratcheting up expectations that future tests will show narrowing disparities.

De Blasio stressed that test scores are just one measure of the school system’s quality and has previously pointed to graduation rates, declines in chronic absenteeism, and other metrics. But he also seemed to acknowledge the political stakes attached to future scores.

That will be “a test,” de Blasio said, “we cannot fail.”