Republican leader Mitch McConnell, 78, on Thursday revealed he had not been to the White House since August because of the way it has handled Covid-19.
The Kentucky senator said he spoke to the president frequently over the phone but had not visited since 6 August.
Mr McConnell, a polio survivor, contrasted the White House with the Senate, where lawmakers are urged to wear masks and social distance.
His comments come as the White House deals with a Covid-19 outbreak.
Since President Donald Trump's Covid-19 diagnosis, at least two dozen people in his circle and staff at the White House have reported infections. First Lady Melania Trump, press secretary Kayleigh McEnany and adviser Stephen Miller are among the positive tests.
Two Republican senators - Mike Lee and Thom Tillis - have also tested positive after attending a White House event, though it is unclear where they caught the virus.
Another Republican Senator, Ron Johnson, who did not attend the event, has also tested positive.
As many as 34 White House staff and "other contacts" have been recently infected with the virus, an internal federal emergency management memo viewed by ABC News said. The memo did not offer details on these additional contacts.
What did McConnell say?
Speaking to reporters in Kentucky, Mr McConnell said he steered clear of the White House in the last two months "because my impression was their approach to how to handle this was different from mine".
He later also noted that he "personally didn't feel that they were approaching the protection from this illness" in the way he felt "was appropriate for the Senate".
While the top Republican has called for masks and distancing, he has stopped short of enacting a mask mandate in the Senate. As the majority leader of the upper chamber, Mr McConnell is responsible for making such rules.
At the end of July, his House of Representatives counterpart, Democratic Speaker Nancy Pelosi, ordered face coverings be worn in the lower chamber after a congressman tested positive.
Both lawmakers rejected an offer from Mr Trump to have rapid Covid-19 tests available for lawmakers, however.
Mr McConnell continued his apparent subtle critique of the White House when he mentioned the struggles of "other places that have had a different view", regarding a different approach to protections.
"And they are, you know, paying the price for it," the top Republican said, adding that the Senate was operating normally thanks to its Covid-19 precautions.
Mr McConnell also emphasised mask-wearing and social distancing were the best way to combat the virus until a vaccine is available.
"It's the only way we know of to prevent the spread until we get a vaccine."
What's the situation at the White House?
Before Mr Trump's diagnosis last week, the White House was conducting frequent rapid virus testing of anyone in Mr Trump's presence.
But experts have said the president and his staff were too reliant on testing over other precautions, like masks and distancing.
Mr Trump returned to the Oval Office on Wednesday afternoon and has been keen to resume work and campaign activity even as many of his aides are still in self-isolation.
On Thursday, Mr Trump told Fox Business he does not believe he is at all contagious. "I think I'm better to the point where I'd love to do a rally tonight," Mr Trump said.
In the same interview, the president also said he would not take part in a virtual debate against 2020 rival Joe Biden, calling it "ridiculous".
There have been some Covid-19 changes at the White House since the president's hospital stay, however.
More staffers are reportedly wearing masks. Traffic in the West Wing and Residence is limited. Anyone interacting with the president has donned full protective equipment, according to chief of staff Mark Meadows.