CRESTON, IOWA - NOVEMBER 25: Democratic presidential candidate South Bend, Indiana Mayor Pete Buttigieg speaks to guests during a campaign stop at the YMCA on November 25, 2019 in Creston, Iowa. The 2020 Iowa Democratic caucuses take place on February 3, 2020, making it the first nominating contest for the Democratic Party to choose their candidate to face Donald Trump in the 2020 election. (Photo by Scott Olson/Getty Images)
Buttigieg bumps up in our 2020 rankings
02:35 - Source: CNN
CNN  — 

South Bend, Indiana, Mayor Pete Buttigieg and Massachusetts Sen. Elizabeth Warren are engaged in a full-blown competition over which candidate is more transparent.

The back and forth has caused each candidate in recent days to disclose more information from their past as they try to outmaneuver one another in a battle that has become increasingly heated with the Iowa caucuses looming less than eight weeks away.

The latest development came Tuesday, when Buttigieg released a list of the nine clients that he worked for at the elite consulting firm McKinsey after facing pressure from Warren and the New York Times Editorial Board, to do so. A day earlier, on Monday, the Buttigieg campaign said it would open its previously closed-door fundraisers to the press and would reveal its campaign bundlers, two moves again that Warren had called on him to make.

On Sunday night, Warren listed the income she earned from her corporate client work after Buttigieg’s campaign called on her to release tax returns from those years.

The conflict has dominated the 2020 news cycle in recent days and shows how the two Democrats view each other’s as threats to each other’s paths to winning the party’s presidential nomination. Former Vice President Joe Biden and Vermont Sen. Bernie Sanders – the two other candidates in the top tier in early voting contests – have largely stayed out of the scrum as Buttigieg and Warren try to land damaging blows on each other’s campaigns.

Buttigieg surged ahead last month in the Iowa polls conducted by both CNN/Des Moines Register/Mediacom and Monmouth University. When Buttigieg rose to that top position in the CNN Iowa survey, pollster J. Ann Selzer notes that Warren got the most second-choice votes among Buttigieg’s supporters.

Patrick Murray, director of the Monmouth University Polling Institute, notes that they are also sparring to be the candidate who is “something new, something fresh, and can beat Donald Trump.”

“Buttigieg as been able to portray himself as kind of every man to every voter,” Murray said.

“For Warren, (Buttigieg) is a threat, because he has taken that spot as the newer candidate that voters are flocking to,” Murray said. “As she started losing that, the drift seemed to go toward Buttigieg – not because they were alike ideologically, but because voters are looking for somebody who is not Biden and not Sanders, who can fight Donald Trump and doesn’t have any baggage.”

The root of their conflict can be traced directly to the wavering voters Warren and Buttigieg are competing for. But their fight goes beyond demographics and ideology.

Buttigieg’s voters tend to be more moderate; Warren’s are more liberal. Warren, a former Harvard Law School professor, and Buttigieg, who attended Harvard and won a Rhodes scholarship, have strong overlapping support among college-educated voters, who form a majority of the electorate. (CNN exit polls show that college educated voters of all races made up 53% of the electorate in 2016, compared to 46% in 2008).

Buttigieg’s campaign has tried to tarnish Warren’s image as a crusader against corporations by noting her early work for corporate clients. Beyond his issues with her corporate legal work, Buttigieg has argued that Warren’s ideas are unworkable. In the CNN October debate, he accused Warren of embracing “infinite partisan combat.”

“Yes, we have to fight,” the South Bend mayor said. “Absolutely we have to fight for the big changes at hand. But it’s going to take more than fighting. … Think about what the President can do to unify a new American majority for some of the boldest things that we’ve attempted in my lifetime.”

When the Buttigieg campaign agreed to open fundraisers on Monday, Warren told reporters she was “glad to see the mayor take these steps.”

“I believe that in 2020 the Democrat who has the best chance to beat Donald Trump is one who makes the case for bringing out corruption,” she said after an event in Las Vegas. “That’s why I’ve based my campaign, from the very beginning on not selling access to my time, not giving special titles to bundlers, never having closed door fundraisers. I’ve just never done that.”

Asked last week why she had begun calling out Buttigieg by name, Warren said it was time for Democrats to draw a clear contrast with “the most corrupt President in living memory.”

“We’ve got a chance to do it a different way,” she said on Saturday in New Hampshire, before making a direct comparison between her campaign and Buttigieg’s. “That doesn’t not involve going behind doors with millionaires and billionaires, putting together bundling programs get special access to the candidate, or they get special perks in the campaign simply because they’re raising buckets of money from their wealthy friends. We have a chance in 2020, as Democrats, to build a grassroots campaign, the kind of campaign that will gives comparative advantage against Donald Trump in November 2020.”

More than a month ago, Warren made a notable change to the concluding portion of her stump speech during the Iowa Democrats’ Liberty and Justice Celebration dinner. Washington insiders, pundits and people in her party, she said, “think that running a vague campaign that nibbles around the edges is somehow safe.”

“It’s easy to give up on big ideas, you can make yourself sound very sophisticated, very smart, give up on big ideas. But when you give up on big ideas, you give up on the people whose lives would be touched by those ideas,” Warren now says as she concludes her many of her speeches.

“I’m not running some campaign that has been shaped by consultants and that has tepid ideas that are designed to offend no one. I gave up on that a long time ago. I am running a campaign based on a lifetime of fighting for working families. I am running a campaign from the heart, because 2020 is our time in history.”

In continually making that contrast, there is little doubt which candidate she is talking about.

CNN’s Daniella Diaz contributed to this report.