Earlier quoted context omitted.
First endorsement in the official party platform, which is a specific document released by the parties every 4 years (except this year for Republicans who re-adopted their 2016 platform with no changes...).
With some qualifiers this is technically correct, but this only makes it feel more disingenuous.
A page on the Obama administration website reflected the personal opinion of the president at the time it was posted, and can be changed at any time.
The presidential nominee is not necessarily going to agree with the party platform (although they are more or less telling voters they will uphold it). The party and all of its delegates certainly need not agree with everything the president says.