Washington (CNN) 2020 Democratic contender Pete Buttigieg has raised over $7 million in the first quarter of the year, the South Bend, Indiana, mayor announced on Twitter Monday morning.

Buttigieg is the first Democrat to publicly reveal his first quarter figure, so it's unknown how his total compares to other candidates. Given the first-day hauls of rivals such as Bernie Sanders and Beto O'Rourke , he's likely to be outraised during the quarter, though it's an impressive amount for a little-known 37-year-old mayor of a small town who is trying to break through a crowded field of better-known Democrats.

"This is just a preliminary analysis, but our team's initial report shows we raised over $7 million dollars in Q1 of this year. We (you) are out-performing expectations at every turn. I'll have a more complete analysis later, but until then: a big thank you to all our supporters," he tweeted

Buttigieg's announcement comes a day after the end of the first fundraising quarter of the 2020 campaign. The totals will offer an early measure of the potency of their White House bids.

The top-tier candidates are aiming to post big numbers. Lesser-known candidates like Buttigieg had faced an added challege: meeting the new criteria the Democratic National Committee has established for the first two debates.

To get on the debate stage this summer, candidates must either earn at least 1% support in several polls or receive campaign contributions from 65,000 individuals. In March, Buttigieg announced in a tweet that he hit the "65,000 donor goal in order to be invited to the first debate."

Buttigieg launched an exploratory committee for a 2020 presidential bid in January, but has not officially launched a campaign. Two of those who have -- Sanders and O'Rourke -- posted large early fundraising hauls, with Sanders raising $5.9 million and O'Rourke raising $6.1 million in the first 24 hours after their respective announcements.

Buttigieg saw a wave of donations to his exploratory committee last month, following an attention-getting CNN town hall.

And in another sign of growing interest in his candidacy, Susie Tompkins Buell, a Democratic donor in California who already backed Sen. Kamala Harris early in the 2020 primary, told CNN on Monday that she will host an event this month for Buttigieg because of the impact she believes he can have on the race.

"He needs to be part of the conversation," Buell said in an email to CNN. "He will bring the level up greatly."