South Bend, Indiana Mayor Pete Buttigieg is rising in the polls and therefore, is starting to face criticism from fellow Democratic presidential contenders who see him as a threat. While most would say this is only natural, MSNBC Morning Joe co-host Mika Brzezinski expressed deep concern on Tuesday that Buttigieg is now receiving criticism.

After highlighting a New Hampshire poll that showed Buttigieg in third place at 15% and within striking distance of Joe Biden's second place position at 18%, the morning show then moved into a controversy that has arisen between Buttigieg and the Bernie Sanders campaign. Fellow co-hosts Joe Scarborough and Willie Geist thought the outrage from the Sanders campaign following Buttigieg comparing Sanders' appeal to Trump's was unfounded as both have prided themselves on being anti-establishment outsiders. The spat then transitioned to an article by NBC reporter Josh Lederman that detailed how Buttigieg's rivals are scrambling to conduct opposition research on him.

While Geist was explaining that Buttigieg and Sanders are quite close politically, Brzezinski interjected, "Who's doing this?" Geist continued to say that while he thought that the Sanders campaign's complaints were unfounded, "It's not to say Mayor Pete is above dirt in a presidential campaign or above criticism, but it does point to the fact, he's caught the attention of this field, having come out of nowhere." Lederman agreed and argued that Buttigieg's previous status as an unknown is behind the dirt digging.

Still, Brzezinski was not thrilled that Buttigieg was coming under even the slightest criticism, asking Capitol Hill correspondent Kasie Hunt if trying to "sully up Mayor Pete" was counterproductive and adding that "It's not going to work."

Hunt instead argued that such criticism was to be expected: "This is what happens when you join the big leagues." She then asked Lederman what areas of vulnerability Buttigieg might have among Democrats. Lederman cited his decision as mayor to demolish abandoned houses and the controversy behind the demotion of the city's black police chief as well as his association with consulting firm McKinsey & Company. But, Brzezinski was still unconvinced, telling Washington Post columnist Eugene Robinson, "I'm skeptical just because I feel like these efforts are going to look really forced."

Robinson, following the pattern of the other panelists, said that criticism of Buttigieg from fellow Democrats is only natural as he rises in the polls. "He is Mayor Pete, he's not Saint Pete" he told Brzezinski, adding that opposition research is just another form of vetting and that receiving criticism will be a good test for because, if he were to get the nomination, surely "Republicans would go after him in this way."

Brzezinski concluded by saying that attacks on Buttigieg will fail in the same way attempts to "make Joe Biden look like a pervert" failed.

Here is a transcript for the April 23 show: