The 37-year-old Rhodes scholar and Afghanistan war veteran is the two-term mayor of his hometown of South Bend -- a left-leaning bubble in America's so-called "Rust Belt" region, where the decline of industries such as steel and automobile manufacturing has hurt local economies.
Voters in states such as Michigan and Wisconsin helped hand Republican US President Donald Trump his victory in the 2016 election.
Buttigieg, who is credited with helping turn South Bend around, has couched himself as a can-do reformer who can speak to voters across the political spectrum.
"Here you have this moment, probably the only moment in American history, where it just might make sense for somebody my age, coming from experience in the industrial Midwest, non-federal, different background, bringing something that will actually help Americans," Buttigieg told NBC's "Meet The Press" last weekend.
Buttigieg was expected to officially launch his candidacy Sunday afternoon in South Bend, giving his already surprisingly strong campaign an additional boost.
In the three months since he declared an exploratory committee to test a presidential run, he has gone from relative obscurity to drawing large crowds at campaign stops.
He has raised $7 million dollars, more than most other candidates, and jumped to third place in the latest polls of voters in Iowa and New Hampshire -- the earliest states to vote in next year's primary elections.
- Buttigieg versus Pence -
The popular mayor who speaks eight languages and plays classical piano has been the focus of countless news stories and profiles.
The fascination has been in no small part due to his background: he would be the youngest, first openly gay, first millennial, and first mayor to become president.
He has had headline-grabbing moments, the most recent being his faith-based challenge of Vice President Mike Pence's views on same-sex marriage and LGBT rights.
Former Indiana governor Pence, a religious conservative, infamously supported a 2015 law that was widely interpreted as codifying discrimination against LGBT people. It was quickly changed after nationwide outrage.
"Speaking only for myself, I can tell you that if being gay was a choice, it was a choice made far, far above my pay grade," Buttigieg said in an April 7 speech.
"And that's the thing I wish the Mike Pences of the world would understand, that if you've got a problem with who I am, your problem is not with me. Your quarrel, sir, is with my creator."
It was a soundbite-ready moment -- like several others he has enjoyed -- that replayed throughout the week in American media.
- 'Destined for national politics' -
Buttigieg's Sunday launch event was scheduled to take place at an expansive South Bend building that once housed an assembly plant for defunct auto manufacturer Studebaker.
The plant's closure in 1963 still reverberated in the city in 2011 when he was elected mayor. He set out to tear down decaying, abandoned homes and restore the blighted Studebaker complex to make it suitable for new high-tech companies.
In an unlikely feat, the city has reversed decades of population decline and attracted new businesses and development, with the mayor's popularity growing in the process.
"His appeal, for many people in South Bend, is his ability to look forward and to focus on better days ahead," South Bend-based political science professor Elizabeth Bennion of Indiana University told AFP.
"Once people looked at his resume and heard him speak, many started talking about the fact that he was destined for national politics."