Sen. Tammy Baldwin, D-Wis., a steadfast ally of President Joe Biden, will be absent from Biden's visit to her hometown of Madison Friday.
The snub comes in the wake of Biden's widely criticized performance during last week's presidential debate, the New York Post reported.
The senator's opponent, Republican Eric Hovde, was endorsed by former President Donald Trump.
The Post reported Baldwin has chosen to distance herself from the president and that she declined to comment on the debate or the calls for Biden's replacement at the top of the ticket.
"Tammy Baldwin is running her own race for the people of Wisconsin," said her campaign spokesman, Andrew Mamo. He later added, "Tammy supports the president."
Baldwin, 62, will continue her previously planned campaign activities in northern Wisconsin instead of joining Biden in Madison.
Polls indicate a tighter race for Biden in Wisconsin than for Baldwin. Despite winning Dane County by over 52 percentage points against Donald Trump four years ago, Biden now trails Baldwin in the Badger State. The RealClearPolitics polling average shows Baldwin leading Hovde by 7.8 percentage points, while Biden and Trump are neck and neck.
"After being a rubber stamp vote for the disastrous Biden agenda for nearly four years, Sen. Baldwin is now making up excuses to not be seen with President Biden," Hovde spokesman Zach Bannon told the Post.
According to ABC News, Baldwin voted with the White House position 96.4% of the time in 2023.
Baldwin, along with other Democratic senators from battleground states, declined an invitation from the White House earlier this month to appear with Biden as he unveiled his new border policy. In a recent podcast interview, Baldwin remarked that her only criticism of Biden's campaign was his failure to highlight his legislative achievements sufficiently.
The Republican Senate campaign arm released an ad last Friday linking Democrats to Biden's debate performance. The video featured Baldwin, Michigan's Elissa Slotkin, Ohio's Sherrod Brown, and Montana's Jon Tester defending Biden, interspersed with clips from the debate.
"Senate Democrats have spent years propping up Joe Biden despite his obvious mental deficiencies; now the world can see he isn't fit for the job. This disaster is on their hands," said Philip Letsou, deputy communications director for the National Republican Senatorial Committee.
Democratic strategist and CEO of Michigan's Grassroots Midwest, Adrian Hemond, emphasized the significance of Biden's performance in down-ballot races.
"The debate performance matters, just like everything else that happens at the top of the ticket matters to people who are running for down-ballot offices," he said.
Information from The Associated Press was used in this report.