On Sunday, South Bend Mayor Pete Buttigieg — the fastest-rising Democratic candidate in the large and growing field of presidential hopefuls — officially announced his presidential campaign, exiting the lengthy exploratory portion of his 2020 bid at an event inside the once bustling Studebaker plant that, when hollowed out after the company left in 1963, was a tangible symbol of his hometown’s march toward decay.

“My name is Pete Buttigieg. They call me Mayor Pete,” Buttigieg told a cheering crowd. “I am a proud son of South Bend, Indiana. And I am running for President of the United States.”

Just more than a month ago, Buttigieg was a largely unknown Midwestern Democrat who decided to run for President.

It has been a whirlwind few weeks for Buttigieg: The mayor has crisscrossed the country looking to seize on the boost he received from a well-reviewed CNN town hall in early March, hopscotching between early nominating states and a string of fundraisers in Democratic strongholds like San Francisco, Chicago and New York. The uptick in interest among Democratic heavyweights has followed a similar uptick in polls, where Buttigieg has gone from receiving less than 1% of support to solidly standing among candidates like Sens. Kamala Harris, Elizabeth Warren and Cory Booker.

By Buttigieg’s own admission, the experience has been “heady,” but now, the mayor said, it’s time to make it official.

“What we’ve seen as we’ve explored is that we’re exploring some really beautiful territory and now it’s time to make it official and announce a decision,” Buttigieg said on Friday as he made his way back to South Bend after a whirlwind trip through California that included an appearance on “Ellen” and a top dollar fundraiser in the Bay Area.

“We’ve been talked about in the 2020 context in a pretty big way for going on a month now,” Buttigieg said. “Then again, if you want to talk about a period of time where you really learn how seriously your effort will be taken and how much momentum you can put together and the resources you can put together, a month isn’t that long at the time.”

Buttigieg announced the exploratory committee at a January news conference in Washington, DC. He told CNN in late March that while, “all of the indicators are pointing” toward an official campaign, “a launch is something you only get to do once, and we’re not going to do that until we have all of the pieces in place.”

Buttigieg will make the announcement on Sunday at Studebaker Building 84, a newly renovated mixed-use building that once housed Studebaker, an auto-manufacturing company that was headquartered in South Bend until it shuttered in 1963.

That wasn’t always the plan: Initially, Buttigieg’s nascent team has planned to basically shut down parts of South Bend’s downtown and hold an outdoor rally in the heart of the city center that has been revived under the mayor’s tenure. Rain and wind meant they had to change plans, but Buttigieg said there is a silver lining in the change.

“The rain location may be a blessing in disguise because there is such symbolic power in that building and you can see in it the past, the present and the future,” he said. “I talk so much about how we’re not looking to turn back the clock and it’s not about retrieving some impossible again. That building is kind of a living symbol of all of that.”

The building has recently been repurposed. It now anchors South Bend’s Renaissance District and houses a mix of technology companies, including South Bend Code School and an Amazon Web Services company, a symbol — Buttigieg is expected to say — of how his leadership as mayor over the last eight years helped revitalize portions of the city.

A senior aide says he will focus on two key topics: The need for generational change in the country and the argument that he is an entirely different political figure at a time when the American people are looking for something different in their politics.

Buttigieg will be introduced on Sunday by a series of mayors.

Although Buttigieg is making his announcement official on Sunday, he officially dropped “exploratory” from his committee with the Federal Election Commission on Friday.

Buttigieg’s committee has been shoestring for months. According to the Buttigieg aide, the committee currently has 32 people on staff and plans to get to 45 or 50 staffers by the end of the month.

That initially small staff has meant the mayor has spent very little of the $7 million his team raised in 2019’s first fundraising quarter. According to the aide, Buttigieg’s first quarter fundraising report will show he only has a burn rate of less than 10%, a number far smaller than other candidates, like Warren, whose campaign announced earlier this month her burn rate was more than 85%.

“Pete’s a different kind of candidate and we want to build a different kind of campaign,” said Mike Schmuhl, Buttigieg’s campaign manager. “We don’t want to a top down, consultant-laden operation. We want to be more like a startup, and we want to build in a smart way and a steady way.”

Schmuhl said that, right now, the campaign does not have any pollsters or consultants. While he didn’t rule them out in the future, Schmuhl said the campaign is looking to be “nimble as we go along.”

The campaign has already opened a campaign headquarters in South Bend, two small suites in the Jefferson Centre building. The campaign also has plans to open a small office in Chicago, where a few aides will live and, given the relatively small size of South Bend’s airport, the candidate and campaign aides will work ahead of flights around the country.

Buttigieg’s rise has also seen him get accepted to the upper echelon of Democratic donors, many of whom are looking to donate to multiple candidates as the field continues to grow.

One of those donors is Susie Tompkins Buell, who — while supporting Harris — also hosted a fundraiser for Buttigieg and around 150 donors on Thursday in the Bay Area.

“He made a very big impression on, I think, everyone. He is very authentic, and this is what people are craving,” she said. “That is one thing he has in common with the current president: What you see is what you get. Otherwise, they are complete opposites.”

The mayor has also not been the only Buttigieg to experience a bump in notoriety. So, too, has Chasten Buttigieg, the mayor’s husband and a teacher, who has become an omnipresent feature of political Twitter and, according to aides, is slated to do a number of solo speeches, primarily to LGBTQ and education groups.

Buttigieg will follow up his announcement with a trip to New York for a low-dollar fundraiser in Brooklyn on Monday, followed by a two-day trip to Iowa on Tuesday and Wednesday.