Giuliani was admitted to Georgetown University Hospital on Sunday, a source familiar confirmed to CNN.
There have been no additional details provided about his condition, and it is unclear when Giuliani received a positive test for Covid-19. He and his spokeswoman have not responded to CNN’s requests for comment.
Giuliani has repeatedly disregarded public health guidelines, appearing maskless in state capitols, hotel ballrooms and at indoor news conferences in recent weeks. At many of the events, most of the other people in the indoor settings were also not wearing masks.
At some of those events, Giuliani was spotted shaking hands, hugging and taking pictures with people while not wearing a mask.
He was most recently at the Georgia Capitol in Atlanta on Thursday to attend a Georgia state Senate hearing on the November election. During a break in the hearing, Giuliani removed the mask he was wearing to greet and take pictures with supporters.
He traveled to Michigan on Wednesday for a state House committee hearing that lasted four and a half hours, during which he was maskless as he pushed misleading claims that the election was stolen from Trump.
Hours before Trump announced his diagnosis, Giuliani was interviewed on Fox News via satellite.
The 76-year-old is considered at high risk for complications from the coronavirus due to his age.
Giuliani has been traveling with Trump campaign attorney Jenna Ellis, who has appeared at his side at all of the events about the 2020 election in the last week.
Ellis on Sunday tweeted out “prayers for Mayor @RudyGiuliani” and called him a “tough warrior.” She vowed the President’s legal team will continue its efforts to overturn the election results.
Trump campaign communications director Tim Murtaugh declined to comment on Giuliani’s condition or whether Ellis has tested positive or plans to quarantine. He referred CNN to tweets by Trump and Ellis.
Last month, Giuliani’s son, Andrew, who is a White House staffer, tested positive for Covid-19 after attending a Trump campaign legal team news conference with his father in Washington, DC.
Andrew Giuliani posted on Twitter Sunday night that his father is “resting, getting great care and feeling well.”
Giuliani also eschewed US Centers for Disease Control and Prevention quarantine guidelines after his son, and close contact and campaign adviser Boris Epshteyn, tested positive in late November. The day Epshteyn announced he had tested positive, Giuliani traveled to Gettysburg, Pennsylvania, where he addressed a group of Republican state lawmakers in a crowded hotel ballroom.
Giuliani was also in close proximity with Bill White, a Trump booster in Georgia who attended the President’s rally Saturday night in Valdosta. White shook hands and closely embraced Giuliani last week.
Georgia Democratic state senator Elena Parent, who attended the hearing at the Georgia Capitol on Thursday with Giuliani, told CNN that Giuliani and his team “willingly endangered all of us to pander to Trump.”
“It was reckless and irresponsible for the Georgia Senate Republicans to hold an in-person hearing without requiring masks and social distancing during a pandemic. Clearly the COVID risk from (Giuliani) and team, who have been attending hearings maskless all around the country, was high and they willingly endangered all of us to pander to Trump,” Parent said in a statement emailed to CNN Sunday.
She added, “Mayor Giuliani’s blatant disregard for public safety measures in this pandemic is irresponsible and puts Georgians in danger.”
This story has been updated with additional reporting.
CNN’s Annie Grayer, Wesley Bruer, Hollie Silverman, Mel Alonso and Donald Judd contributed to this report.