(CNN) Former Vice President Joe Biden's 2020 campaign raised $21.5 million in the second quarter, his campaign announced in an email to supporters on Wednesday.

The number puts Biden behind South Bend, Indiana, mayor Pete Buttigieg , who raised $24.8 million in the second quarter, but ahead of Vermont Sen. Bernie Sanders , who announced an $18 million haul on Tuesday. Biden, however, entered the race a little more than three weeks after the start of the fundraising quarter, meaning Buttigieg and Sanders had more time to raise money.

The fundraising announcement comes as Biden embarks on his longest stretch on the campaign trail since announcing his 2020 bid in April. He's in Iowa Wednesday and Thursday, before heading to Houston on Friday and South Carolina on Saturday and Sunday. Biden has plans to go to New Hampshire next week.

The former vice president is hitting the campaign trail after the first Democratic debate, where he took a hit from California Sen. Kamala Harris over his past opposition to desegregation busing. Polls conducted after that debate, including one by CNN , show his numbers have dipped significantly, although he still maintains a slight lead over the Democratic field.

CNN's Chris Cuomo will sit down with Biden in Iowa in an interview that will air on Friday. It is one of only a few national television interviews Biden has done since he announced his candidacy.

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