“To have sold and then bought stocks that benefit them personally is just very, very frustrating,” Collins said. "And it's very disheartening for those of us who have been in public service."

“This is just not something you want to see, being perceived as profiting off a crisis,” Collins added, though he did not call on her to resign or face an Senate Ethics Committee investigation.

Loeffler denied doing anything inappropriate, saying the stocks were sold by third-party financial advisers, and that she did not use information from private briefings about the coronavirus to benefit herself financially. She reported selling between nearly $1.3 million and $3.1 million worth of stocks owned jointly with her husband between late January and mid-February. She also reported jointly purchasing between $200,000 and $500,000 of stock in two technology companies.

“I don't direct the activity. I'm not involved in the investment decisions,” Loeffler said in an interview on CNBC Friday afternoon. “I made that decision many years ago for the position I had in financial services — that I would not get involved in investment decisions."

The Georgia special election is already perilous for Republicans, given that it is an all-party contest that will go to a January runoff if no candidate receives a majority in November — a likely outcome given the crowd of contenders. Three Democrats are in the race currently: Rev. Raphael Warnock; former U.S. Attorney Ed Tarver; and Matt Lieberman, son of former Sen. Joe Lieberman (I-Conn.). Warnock has endorsements from the Democratic Senatorial Campaign Committee and Stacey Abrams, the former gubernatorial candidate.

Loeffler has the backing of the National Republican Senatorial Committee and Gov. Brian Kemp, who appointed her to the seat to replace Sen. Johnny Isakson, who resigned late last year due to health concerns. But Collins also has some significant allies in the state, and he is running an insurgent campaign attempting to outflank Loeffler as an ally to Trump, who has not taken sides in the race.

One Georgia Republican operative, who requested anonymity to speak candidly, said Loeffler was in a “perilous” political situation caused by the revelations about her stocks specifically because, in the all-party November contest, another Republican was on the ballot.

“They can't just appeal to partisan loyalties and say, 'Don't believe these storylines. This is a media attack,'” the operative said. “People have somewhere else to go if they're uncertain about her, and that's a really dangerous place to be.”

The accusations of self-dealing while the U.S. copes with the unprecedented coronavirus crisis — combined with reports that other senators, including Intelligence Chairman Richard Burr (R-N.C.), also sold off stocks before the market crashed — represent a major early test for Loeffler, a first-time political candidate on whom Republicans are counting to keep a contested Senate seat in GOP hands as Democrats mount a charge to retake the chamber in this year's elections.

Some Democrats immediately called for Loeffler's resignation following the initial report from The Daily Beast about the transactions, which came in the days and weeks following a private briefing for senators on the coronavirus. Others called for an investigation by the Ethics Committee.

Lieberman said in a statement that Loeffler’s actions were “incredibly disappointing and shameful.” Warnock, national Democrats' preferred candidate in the race, called the transactions “deeply disappointing” and said they should be investigated.

Tarver, the former U.S. attorney, said Loeffler should resign.

“This is more than just poor judgment,” Tarver said. “This is downright wrong and everything that’s wrong with Washington. We’re in the middle of a pandemic the likes of which many of us having never seen. We need honest leadership in Washington, and it’s clear we’re not getting that with Sen. Loeffler.”

Stephen Lawson, a spokesperson for her campaign, said Loeffler "has done absolutely nothing wrong" and hit both Collins and Democrats for "spending their time launching baseless attacks" against the senator.

Burr, who also faced swift condemnation for his sale of stocks in recent weeks, asked the Ethics Committee to review the matter. Loeffler, who did multiple cable news interviews Friday to push back on the reports, said in the appearance on CNBC that she was “happy to answer any and all questions and would submit to whatever review is needed,” but she has not called on the Ethics Committee to look into the matter.

“I think we have to make sure that all the rules and laws are followed,” Loeffler said on CNBC. “I think they are being followed, at least in my case I know they are. I can't speak for other people. But that's certainly what securities laws are for. That's what ethics rules are for. That's what I'm very confident we are complying with, have always complied with and will continue to do."