WASHINGTON — Sarah Huckabee Sanders had her trial by fire Tuesday and Wednesday. She stayed cool, despite the heat.

With White House press secretary Sean Spicer sidelined, Sanders, Spicer's deputy, got the call to explain why President Donald Trump fired FBI Director James B. Comey.

Sanders tried. It wasn't easy.

In only her second time running the official daily news briefing, Sanders told reporters that Comey had lost the confidence of her boss "from the day (Trump) was elected."

That struck many as questionable. Trump openly cheered Comey's actions on the campaign trail, especially when he announced in late October, just days before Election Day, that he was reopening an investigation of Democratic challenger Hillary Clinton's emails. Spicer said Trump "has confidence in the director" just a week ago.

Nevertheless, Sanders persisted, saying Democrats should welcome his ouster.

"I think that Director Comey has shown over the last several months and, frankly, the last year, a lot of missteps and mistakes," she said. "As you've seen from many of the comments from Democrat members ... they thought he should be gone. Frankly, I think it's startling that Democrats aren't celebrating this, since they've been calling for it for so long."

She offered an extreme characterization of Comey's actions, raising more than a few eyebrows among reporters when she said he had committed "atrocities" by circumventing the Justice Department's chain of command and repeatedly going public with details of the email inquiry.

Barely discussed or even mentioned: that Comey also was leading the FBI's investigation of the Trump campaign's potential ties to Russia, a topic that drives Trump into Twitter rages. And contrary to the apparent expectations of the White House, the president's critics went directly to the Russia matter.

Sanders was like the understudy who gets pressed into the lead role after the star suddenly becomes incapacitated. Spicer, who has done the hard work of defending Trump even before the inauguration, was out of action Wednesday serving Navy Reserve duty at the Pentagon.

The spin from Sanders — whose official title is principal deputy press secretary - may not have been wholly different from what you may have expected from Spicer. But her manner certainly was. Sanders kept her answers short and crisp, and rarely interrupted her questioners with Spicer-ian interjections of "Hold on!"

Sanders, 35, is the daughter of Mike Huckabee, a former Arkansas governor and Republican presidential candidate. Her official baptism in politics came through her father; as a college student, she was the field coordinator for his 2002 re-election campaign.

She subsequently worked for Republican candidates, including George W. Bush's re-election campaign in 2004, former Minnesota governor Tim Pawlenty's unsuccessful presidential run in 2012, and the successful 2014 Senate campaign of Tom Cotton, R-Ark.

She became a senior adviser to Trump in 2016 after managing her father's presidential bid, which attracted just one delegate.

Sanders, who did not respond to requests for comment for this article, first tried out her talking points about Comey on Tuesday night. This was shortly after the White House communications staff was caught so far off guard by the news that Spicer briefly ducked into the White House shrubbery to avoid talking with reporters.

Sanders' relative poise in the face of a skeptical news media immediately gave rise to speculation among journalists that she was in line to replace Spicer as Trump's chief spokesperson. There's nothing to support that notion, but that didn't stop CNN from mulling over the possibility.

Another kind of buzz started up on Twitter: Just as comedian Melissa McCarthy has created a franchise by parodying Spicer on Saturday Night Live, Sanders' newly elevated profile must mean that cast member Cecily Strong (whom Sanders resembles) is surely going to play her on Saturday's program.

Sanders took her first crack at heading off the metastasizing criticism of Comey's firing during an interview Tuesday evening on Tucker Carlson's program on Fox News Channel, a safe venue.

"My gosh, Tucker," she said, with mild pique, "when are (critics) going to let that go?" she said of the Russia investigation. "It's been going on for nearly a year. Frankly, it's kind of getting absurd. There's nothing there. We've heard that time and time again. ... There is no 'there' there. It's time to move on."

Carlson didn't challenge her, but the same general line didn't work so well on MSNBC's Morning Joe on Wednesday.

Sanders first claimed that host Joe Scarborough had once said that there was no evidence tying Trump's campaign to the Russian government, bringing a swift retort from Scarborough.

"I said there's no obvious evidence of collusion out there right now," he said. "If there were that obvious evidence of collusion, it would have already been leaked by now. I also said there have to be in-depth investigations because it may take, I think, probably an independent prosecutor to figure out the financial ties between Donald Trump and Russia."

He added, "I'm surprised you're twisting my words."

When Sanders proceeded to argue that committees in the House, the Senate and the FBI have looked into Trump's Russia connection and "everyone comes to the same conclusion," co-host Mika Brzezinski jumped in. She noted that no such conclusion had been reached. "You're not actually telling the truth right now," Brzezinski told her.

White House reporters say they generally like Sanders, who honed her messaging skills as a TV surrogate for Trump during the campaign.

"She's remarkably poised for her age," said one, who like several interviewed, spoke on the condition of anonymity to avoid crossing a key White House source. "She has her father's sense of humor, which is a good thing. People who've held that job before are humorless."

Another reporter noted that Sanders was dealt a poor hand, but played it about as effectively as she could.

"You can only do so good of a job if you're spinning on behalf of a president whose story changes minute to minute," she said. "She remained calm. ... She has a steadiness that Spicer evidently lacks."

But that's not to say the reporter is rooting for Sanders to replace Spicer. "He's a very complex character, and he makes a lot of fun mistakes," she said. "And you can see, on his face nearly every day, that he struggles with this job. ... There's a lot going on there, and so he's a rich subject."