After rising from relative obscurity earlier this year, the South Bend, Indiana, mayor has found his campaign steadily atop the second tier candidates in the 2020 Democratic primary, but consistently unable to break into the top tier with former Vice President Joe Biden , Massachusetts Sen. Elizabeth Warren and Vermont Sen. Bernie Sanders

With just over 100 days until the Iowa caucuses, Buttigieg and his team of advisers have decided they can't wait on a front-runner to fade away and believe that now -- with pointed ads and aggressive debate performances -- is the time to make their move. The goal is to peel support away from a cash-strapped Biden and present a more moderate alternative to the liberal views of Warren and Sanders.

To do that, the mayor -- whose rise was centered on the need for comity within the Democratic Party and an intense focus on how to beat President Donald Trump, especially in his native Midwest -- is beginning to take on his Democratic rivals with pointed critiques.

"We are at another level where we need draw distinctions and differences with other candidates," Mike Schmuhl, Buttigieg's campaign manager, told CNN. "A lot of people are drawn to Pete because he is civil and decent and kind. That's who he is. But elections are about choices and they are about differences and they are about distinctions."

Buttigieg, in an interview with CNN, said he still believes in "kindness" and will continue to be the person many of his supporters were drawn to early in the campaign. But he added that this moment in the race is not a time to acquiesce to others.

"Sometimes we need to make sure nobody confuses kindness for weakness," he said.

Going on the attack

The clearest sign of this Buttigieg evolution came in the CNN/New York Times debate earlier this month. Buttigieg squared off with Warren on how she would pay for "Medicare for All," Hawaii Rep. Tulsi Gabbard on her views on war in Syria and former Rep. Beto O'Rourke on mandatory gun buybacks . But his campaign -- at events and in paid media -- had been signaling this change in the weeks leading up to those moments on the debate stage.

Buttigieg, according to data collected by CNN, has spent more than $6.3 million on digital ads, including multiple ads that take on his Democratic opponents who back Medicare for All, the single-payer health care plan that Buttigieg says fails to offer choice to American voters. Buttigieg is also set to spend more than $500,000 on television ads in Iowa in the next two weeks.

And, here in Las Vegas, days after his debate performance, Buttigieg kept up the pressure on Warren, slamming her for not answering how she would pay for Medicare for All. While Sanders, who wrote the bill, has acknowledged the plan would raise taxes, Warren dodged the question during the debate. (She has since promised to release a plan in the coming weeks that explains how she would pay for the proposal.)

"Will taxes go up for your Medicare for all who want it? Yes or no," a voter asked Buttigieg at his East Las Vegas rally, referring to the mayor's more moderate health care plan.

The mayor smirked and replied.

"Good question, because not everyone has been answering this question," the mayor said in a clear knock against Warren. He went on to explain that the Medicare for All Who Want It plan would be paid for by rolling back the corporate tax cuts Trump passed and savings from the federal government negotiating drug prices.

Minutes before that rally, Buttigieg succinctly laid out his argument against candidates like Warren in an interview with the Las Vegas Review-Journal : "Being bold doesn't have to be divisive."

This plan is not without risks. Buttigieg's newfound aggressiveness has made him a newly favorite target of his opponents, with some claiming he is either a corporate politician willing to change his positions for campaign donations or a poll-tested candidate who is willing to change positions for political expediency.

People close to Warren's campaign have accused Buttigieg of being "too corporate" and just as evasive on paying for his health care plan as Warren. They have charged that, in a move for political expediency, he has backed away from supporting Medicare for All.

O'Rourke has said Buttigieg is too "calculating" and poll tested on guns, a charge that Buttigieg dismissed before the debate as the former congressman trying to stay relevant.

And Julián Castro's campaign has rebuked the mayor on immigration, saying Buttigieg was moderating his views on decriminalizing crossing illegal border crossings. Buttigieg faulted those calling for such a plan during the October Democratic debate; months before, at the first debate, he praised such plan.

"Mayor Pete goes from making an impassioned (sic) case for decriminalizing border crossings (which he says is the 'basis for family separation') in debate one, to adding it to his list of policies he calls 'purity tests' in debate four," Castro spokesman Sawyer Hackett tweeted this month. "Who's the real Pete?"

Buttigieg on Wednesday dismissed charges of moderating on liberal policy, telling CNN that he has been "consistent" in his views and that the "left-right framework is less and less useful in understanding this race."

Photos: Former presidential candidate Pete Buttigieg Photos: Former presidential candidate Pete Buttigieg Pete Buttigieg, the former mayor of South Bend, Indiana, poses for a portrait at his office in December 2018. Hide Caption 1 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg was an intelligence officer with the Navy Reserve from 2009 until 2017, and he served in the war in Afghanistan. Hide Caption 2 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg thanks supporters after he was elected mayor in 2011. Buttigieg was born and raised in South Bend and went on to attend Harvard College. He later became a Rhodes scholar. After a three-year stint at the consulting firm McKinsey and Company, Buttigieg came back to Indiana and lost a race for state treasurer in 2010. Hide Caption 3 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg listens to a question during a news conference announcing an interim police chief in March 2012. Hide Caption 4 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg paddles a raft during the East Race Waterway in July 2013. Hide Caption 5 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg delivers his State of the City address in February 2014. Hide Caption 6 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg is welcomed home in September 2014 after serving a seven-month tour of duty in Afghanistan. Hide Caption 7 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg speaks in November 2014 during a presentation ceremony for a newly redeveloped area in South Bend. Hide Caption 8 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg speaks out about the Religious Freedom Restoration Act that was signed in Indiana in March 2015. Buttigieg and other critics of the legislation, which was signed into law by then-Indiana Gov. Mike Pence, contended that individuals and businesses could use it to discriminate against the gay community on the basis of religion. Pence later signed an amendment that was intended to protect the rights of LGBT people. Hide Caption 9 of 28 Photos: Former presidential candidate Pete Buttigieg The State Theater in downtown South Bend shows its support for "Mayor Pete" after Buttigieg came out as gay in June 2015. Hide Caption 10 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg's name is Maltese and roughly translates to "lord of the poultry." His husband, Chasten, tweeted a list of possible pronunciations in 2018 that included "boot-edge-edge," "buddha-judge" and "boot-a-judge." Hide Caption 11 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg speaks at a debate-watching party in Chicago in September 2016. He was stumping for Democratic presidential candidate Hillary Clinton. Hide Caption 12 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg speaks during a Democratic National Committee forum in February 2017. Hide Caption 13 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg greets supporters during the DNC forum in February 2017. He was campaigning at the time to be the committee's chairman. Hide Caption 14 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg walks with Facebook CEO Mark Zuckerberg, a personal friend, who was visiting South Bend in April 2017. Hide Caption 15 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg appears on "Late Night with Seth Meyers" in June 2017. Hide Caption 16 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg kisses his husband, Chasten, after they were married in South Bend in June 2018. Hide Caption 17 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg announces in December 2018 that he would not be seeking a third term as mayor. Hide Caption 18 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg talks with a reporter in downtown South Bend in January 2019. Hide Caption 19 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg speaks to reporters in Washington after announcing his presidential ambitions. Hide Caption 20 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg speaks during the US Conference of Mayors in January 2019. Hide Caption 21 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg speaks during a campaign stop in Ankeny, Iowa, in February 2019. Hide Caption 22 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg signs copies of his book "Shortest Way Home" in February 2019. Hide Caption 23 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg speaks on stage during the South by Southwest Festival in Austin, Texas, in March 2019. Hide Caption 24 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg answers questions from supporters during a fundraising event in West Hollywood, California, in March 2019. Hide Caption 25 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg and former Vice President Joe Biden talk during a break in the first Democratic debates. Hide Caption 26 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg takes part in CNN's Democratic debates in July 2019. Hide Caption 27 of 28 Photos: Former presidential candidate Pete Buttigieg Buttigieg announces the end of his presidential campaign at an event in South Bend, Indiana, in March 2020. Hide Caption 28 of 28

Lis Smith, Buttigieg's spokeswoman, said the South Bend-based campaign welcomes the focus.

"There was a clear and visible uptick towards Pete from our opponents after the debate," Smith said. "That, to us, signaled strongly that he had made the most effective contrast of any candidate during any of the debates."

Some of that is backed up by Buttigieg supporters here in Nevada, who cheered the Democrat's debate performance, including when he rhetorically asked the audience at the start of his rally, "Did I do OK?"

"I think a lot of people have gotten very tired of the rhetoric and the promises and the pie in the sky, unicorn flying over the rainbow," said Mary Figueras, a 61-year old Las Vegan who decided to support the mayor a month ago.

MJ Erani, a Buttigieg supporter who began backing him in January, agreed.

"In the third debate, I think he kind of got lost," she said. "And while I don't need that additional sort of aggressiveness, it seemed like he got a lot more attention and I didn't seem to be negative attention."

But among undecided voters who attended one of Buttigieg's events here in Nevada, the reviews were not as unflinchingly positive.

"He was good. I think he can do it without trying to be overly aggressive," said Enrique Diaz, a 65-year old retiree who likes the mayor but hasn't decided to commit to him. "If you go on offense, it shows for me he has a lack of confidence... like he needs (to do) something. He doesn't need anything because he's very smart, very articulate, very good."

Jesus Sy, a 63-year old retiree who stood waiting for Buttigieg to speak with Diaz, echoed that sentiment.

"He doesn't seem to be a naturally aggressive person," Sy said.

And Matthew DeFalco, an undecided 30-year old Democrat, was even blunter.

"It wasn't bold to me," DeFalco said of Buttigieg's debate performance. "What that was, to me, was more unproductive. It was fighting."

"Everyone has a different plan in this race for how we should approach this problem. But we shouldn't be attacking each other in that way," said DeFalco, who unsuccessfully ran for Henderson City Council in 2017. "It just felt unproductive."

Buttigieg's direct tone is more striking when considering the mayor used some of his earliest appearances and debate performances to slam party infighting. At the third Democratic debate, Buttigieg said a spat between Biden and Castro was "unwatchable."

"This reminds everybody of what they cannot stand about Washington," he said at the time.

But on Tuesday in Las Vegas, the mayor defended the forcefulness of his debate performance, telling CNN that he was not worried it was going to dissuade undecided voters from backing him.

"I think this a season for contrast delivered respectfully," he said. "Whenever I draw a contrast with a competitor its always going to be about policy, it's going to be about substance."