At least I think that is what this means.
Having a majority means having the votes to pass what you want. There may be more Republicans than Democrats in the House, but Republicans are so divided they don't have the ability to pass what they want. So I don't think they can claim to have a majority anymore. The actual majority, the place where the majority of votes are, crosses traditional party lines but also includes a lot more Democrats than Republicans. For all practical purposes, that is where the House majority is.
