Nominations just go through the senate, not the house of representatives. Democrats DO hold a majority in the senate.
I don’t want to let Republicans off the hook – they are obstructionists and government abolitionists, and this is primarily due to Ted Cruz’s opposition – but no, this is happening entirely under a Democratic held chamber.
I just want to point out how common this is, btw: Democrats plead for votes to get control over government, and then when they get it, somehow they still always find a way to insist that they can’t do anything because they just don’t have enough control. Even when they’re in charge, the media and the party advance the narrative that they’re not REALLY in charge.