It comes shortly after the suspension of his campaign for California governor on Sunday, amid allegations of sexual assault made against Swalwell.
However, because Swalwell missed the deadline to formally withdraw, his name will remain on the June 2 primary ballot.
In a post on X, Swalwell apologized to his family and peers.
But he is still maintaining his stance, writing in part, "I will fight the serious, false allegation made against me. However, I must take responsibility and ownership for the mistakes I did make."
The decision was pushed heavily by his fellow congressmembers with many of them prepared to expel Swalwell if he didn't resign.
Valley congressman and Democrat Adam Gray immediately pulled his support of Swalwell after learning of the claims, calling them "deeply disturbing."
Swalwell was the leading Democratic candidate in what remains a crowded race for governor.
"The concern has been that, in this jungled primary, that it could end up being two republicans that come out on top because there's so many democrats running," said Marsha Conant, First Vice Chair of the Fresno County Democratic Party.
The scandal, sure to bring even more eyes to the election, but Monday some top candidates saying it won't make much of an impact.
"I don't view myself as aiming myself towards Eric Swalwell's supporters. I view myself as aiming myself at working Californians who need relief," said Democratic candidate Tom Steyer.
Republican Steve Hilton also addressed the situation, saying, "It'll probably lead to some consolidation on the Democrat side. But in the end, I don't think it makes much difference."
It will now be up to Governor Gavin Newsom to decide if and when Swalwell's seat in Congress is filled.
Newsom's office says they are reviewing the matter, and will make an announcement once the seat is officially vacant.
There are reports that another woman who claims to have "serious sexual misconduct" allegations will hold a press conference in Los Angeles Tuesday describing her claims.
Swalwell's attorneys have said they are prepared to fight any allegations made against him.