I could have sworn I heard Trump say that the FBI should go along with what the senators want as they are running the show there. I did not recall hearing the senate asking for inquiries into other things. IMO this article is a tad over expressive i.e. the Times is trying to gin up a long drawn out witch hunt. In fact, the president said he did not wish to see a witch hunt.
President Trump has been very clear that this investigation belongs to the FBI and the Senators. He did not put conditions on who they could interview, as that would be the Executive branch unduly interfering with a Legislative Branch function.
The Slimes knows this full well but they are trying to make it look like the investigation is being run from the White House, which will then give the Dems cover to say it was not thorough enough to get the whole picture and therefore, it needs to continue until THEY deem it finished, which of course will be when they find that girl on the playground from kindergarten who claims Brett Kavanaugh cut her off in line for the swingset, thereby establishing his lifelong pattern of disrespecting and intimidating women!! (And they will need his mother to produce his Thermos from said timeframe to verify exactly what was in it, since several unnamed sources from the class indicated they possibly smelled some kind of “fruit punch” on his breath at recess on more than one occasion!)