Sen. Chris Murphy (D-Conn.) knocked Republicans on Monday over a largely muted response to a whistleblower complaint reportedly linked to President Trump. 

"This is an extraordinary moment. We're watching this country turn into a banana republic. Republicans better be careful what they wish for because a Democratic president could use the same tools that Donald Trump is using to turn the White House into just one big extension of his reelection campaign," Murphy told reporters. 

"This is just a head shaking moment for me that Republicans don't give a damn about the national security of this country and are willing to let the president get away with this fundamental corruption. If that is the direction that they take—attacking the whistleblower, trying to cover up this corruption, it's a really, really sad day for the country," Murphy added. 

Murphy's comments come after he was told about Sen. John Cornyn (R-Texas) questioning if the whistleblower at the center of the current scandal is a "leaker." 

"Is it a whistleblower or a leaker? I don't know which," Cornyn said, asked about the whistleblower complaint and if it should be turned over to lawmakers. 

Sen. Lindsey Graham (R-S.C.) while urging Trump to be transparent about a phone call with Ukrainian President Volodymyr Zelensky, has also called for an investigation into former Vice President Joe Biden and his son, Hunter Biden. 

"I think the best way to do this, quite frankly, and that’s a good question, is for somebody independent of politics to ... look, it doesn’t have to be a special counsel, but to look at the substance of that interview. Was any money paid to the Bidens, Hunter Biden? What was it paid for? Was there any interaction between the prosecutor being dismissed and these transactions?" Graham told radio host Hugh Hewitt on Monday.  

Several Republican senators declined to directly weigh in on Monday, arguing that they didn't have enough information about the complaint and the allegation that Trump or his lawyer Rudy Giuliani attempted to persuade Zelensky to investigate Biden or his son.

Senate Majority Leader Mitch McConnell (R-Ky.) knocked Democrats for trying to "politicize" the complaint, but sidestepped weighing in on the substance of the allegation against Trump. He noted that Senate Intelligence Committee Chairman Richard Burr (R-N.C.) is trying to set up a closed-door briefing with the intelligence community inspector general. 

Sen. John Thune (R-S.D.), the No. 2 Senate Republican, similarly pointed to the committee as a starting point for lawmakers. 

"My understanding is that Burr is trying to get the inspector general and the DNI to come up in front of his committee. I would prefer because of some of the sensitivity of the national security implications involved in all of this that he started there," Thune said. 

Pressed if he thought the administration should hand over the complaint, he added that they should "proceed with caution." 

"I would hope that whatever information is available that is in possession of the inspector general, of the DNI that we would get access to that," he said.