Lindsay Graham wants Guiliani to testify in front of the Senate Judiciary Committee about corruption in Ukraine. I can't tell if he's trying to torpedo Trump or if he actually thinks this is a good idea.
I think it feels like some combination between "Trump trying to do as much as possible for Russia and himself before being ousted" and "Trump trying to use ever-greater foreign creative destruction to distract from the attacks on him". I honestly don't know if he/whoever is his brains thinks they need to do as much as possible now to ensure a lasting upsetting of the balance (which I'm fairly sure has already been achieved), or if they think they can weather this and just need an ever bigger diversion.
Time for some more quoting of the founding fathers:
"The danger then consists merely in this: the president can displace from office a man whose merits require that he should be continued in it. What will be the motives which the president can feel for such abuse of his power, and the restraints that operate to prevent it? In the first place, he will be impeachable by this house, before the senate, for such an act of maladministration; for I contend that the wanton removal of meritorious officers would subject him to impeachment and removal from his own high trust. But what can be his motives for displacing a worthy man? It must be that he may fill the place with an unworthy creature of his own. "