Ohio Gov. Mike DeWine said he tested negative for the coronavirus, in contrast with test results he received earlier Thursday.
DeWine said he had a PCR test administered after an antigen test earlier indicated he had tested positive for the coronavirus. The earlier test was administered before the Republican governor was scheduled to greet President Donald Trump upon his arrival in Cleveland.
PCR or polymerase chain reaction tests are considered the most accurate kind available on the market, but demand has often overwhelmed supply, leading to delays. These tests detect genetic material related to the virus, while antigen tests look for protein fragments found on or within the virus.
DeWine explained the antigen test was conducted as a part of protocol ahead of meeting with the president. While this kind of test is based off "new technology to reduce the cost and improve the turnaround time," DeWine said his state "does not have much experience with antigen tests."
"We will be working with the manufacturer to have a better understanding of how the discrepancy between these two tests could have occurred," he said.
DeWine said he and his wife would have another PCR test conducted on Saturday "out of an abundance of caution, and at the direction of medical professionals."
The announcement of DeWine's earlier test results came shortly after Trump left the White House to travel to Ohio, where he was set to speak about the economy and tour a Whirlpool manufacturing plant. The president was also scheduled to participate in a roundtable event with his supporters and attend a fundraising committee reception in the evening. Trump was scheduled to travel to New Jersey later in the day.
"I want to just say that a very good friend of mine just tested positive, do you know that?" Trump told a crowd of supporters outside Air Force One after he landed in the Buckeye State.
"Our great governor, governor of Ohio, DeWine, just tested positive, just here. And we want to wish him the best. He'll be fine," Trump said. "But he's a great guy, he's done a fantastic job."
DeWine, 73, was the second governor to have tested positive for Covid-19. Republican Gov. Kevin Stitt of Oklahoma was diagnosed with the virus in mid July.
DeWine had postponed his Thursday briefing on the virus in order to attend Trump's arrival, according to Cleveland.com. That briefing was reportedly postponed until Friday at 2 p.m.
Trump landed before 2 p.m. ET at Burke Lakefront Airport in Cleveland, where DeWine had planned to greet him on the tarmac. DeWine was tested as part of the "standard protocol" for meeting with the president, according to the statement from the governor's office.
His test, which apparently delivered results within hours, came back positive, DeWine's office said.
"The President wishes Governor DeWine a speedy and full recovery and commends the job he's doing for the great state of Ohio," White House spokesman Judd Deere said in a statement to CNBC.
Ohio has been hit hard by the coronavirus. There have been 96,305 total confirmed and probable cases of Covid-19 in the state since the pandemic began, along with a total of 3,596 deaths, according to the Ohio Department of Health.
The coronavirus has infected more than 4.8 million people in the United States, killing more than 158,000, according to data compiled by Johns Hopkins University.
Amid last month's rise in Covid-19 cases, DeWine imposed additional measures to try to slow the spread of the disease in his state.
Ohio last month announced a statewide mask mandate applying to all people in indoor public spaces, as well as in outdoor situations where a social distance cannot be maintained. DeWine has also proposed a plan to stop all alcohol sales at restaurants and bars after 10 p.m. nightly.
-- CNBC's Christina Wilkie contributed to this report.
Correction: Ohio last month announced a statewide mask mandate. An earlier version misstated the timing.