Some Republican lawmakers are considering opening an investigation into the whistleblower when the impeachment trial, and presumed acquittal of President Trump, is all said and done.

The most notable of these is Sen. Lindsey Graham. Graham has warned that the Senate Intelligence Committee will call the whistleblower whose complaint ended up launching the impeachment inquiry against Trump, while the Foreign Relations Committee will likely investigate Joe Biden.

“The Senate Intel committee under Richard Burr has told us that we will call the whistleblower,” Graham said on Fox News’ Sunday Morning Futures. “Why is it important? I want to know how all this crap started.”

Graham went on to say that he wants to know what ties the whistleblower — who first raised a red flag regarding Trump’s phone call with Ukrainian President Volodymyr Zelensky — has with Democrats. “If the whistleblower is a former employee of, associate of, Joe Biden, I think that would be important. If the whistleblower was working with people on Schiff’s staff that wanted to take Trump down a year and a half ago, I think that would be important. If the Schiff staff people helped write the complaint, that would be important.”

Graham added, “We’re going to get to the bottom of all of this to make sure this never happens again.”

Graham isn’t alone in pushing for Biden investigations. Sen. Ted Cruz (R-TX) told reporters on Monday that he also wants to see Senate committees take them up once the impeachment trial has concluded.

“I will confess, prior to the impeachment trial I did not know the full scope of the evidence of potential corruption concerning Joe Biden,” said Cruz. “But the reason the President was particularly justified in asking for this investigation is, if you have corruption that goes to the very highest levels of government that is a serious public concern.”