Senator Mitch McConnell of Kentucky, the longtime Republican leader who has appeared increasingly diminished and frail after a series of falls and a serious head injury this year, froze up suddenly during a news conference on Wednesday in Covington, Ky., the second such episode he has experienced on camera in recent weeks.

Mr. McConnell, 81, was taking questions from reporters after an event hosted by the Northern Kentucky Chamber of Commerce when he was asked for his thoughts on running for re-election in 2026. Mr. McConnell, who appeared thinner and paler than he has in recent months, began to answer the question with a slight chuckle and abruptly stopped speaking for about 30 seconds, standing motionless as he gripped his lectern with his mouth pursed and his eyes fixed.

When an aide approached to ask if he had heard the question, he mumbled “yes,” but he seemed unable to continue speaking or to move.

It was the second such incident in two months, and the scene intensified questions about Mr. McConnell’s health condition, his ability to serve and his future in the Senate.

Mr. McConnell had a concussion in March when he fell at a Washington hotel during a fund-raising event, and was absent from the Senate for weeks while giving almost no updates on his health status. Since then, he has had at least two more falls, which his office did not disclose.

Then last month, Mr. McConnell froze midsentence during an appearance at his weekly news conference in the Capitol and was briefly escorted away from the microphones to recover.

Two neurologists who viewed video of the news conference at the time said it could have been a mini stroke or partial seizure. But Mr. McConnell’s office declined to share details about his health, including whether he consulted with a physician after the incident.

After Wednesday’s episode, a spokesman said that Mr. McConnell had felt lightheaded during the news conference and as a safety measure planned to consult with a physician before his next event. His office provided no further information about the incident.

Mr. McConnell, who was elected to a seventh term in 2020 and this year surpassed Mike Mansfield, Democrat of Montana, for the title of longest-serving Senate leader, has made it clear he has no plans to step down from leading the Republican conference and has not acknowledged any physical ailments.

He has shared little information about his health, trying to project that he is going about business as usual despite repeated episodes that raise questions about his condition. Mr. McConnell, a stubborn survivor who overcame polio in childhood to rise to the pinnacle of politics, has committed his life to wielding power in the Senate, and colleagues and close observers regard him as virtually unable to imagine stepping down.

Even with the Mansfield milestone behind him, and a political party led by former President Donald J. Trump drifting away from him, Mr. McConnell has brushed off any speculation that he would retire. “I’m not going anywhere,” he told reporters earlier this year.

Still, the recent string of medical incidents has made his colleagues concerned about his health and his ability to play a role in leading Republicans. Some have noted that his diminished state has meant that he stayed on the sidelines of the debt ceiling negotiations, something a younger McConnell would never have done and that left many Senate Republicans ultimately unhappy with the outcome of the deal.

Mr. McConnell had to rely on other members of his leadership team, like Senator John Thune of South Dakota, to step in and lead the conference for him when he was absent for weeks, recovering from a concussion. Since then, his health has continued to raise questions about a potential change coming to Republican leadership in the Senate.

On Wednesday, inside a conference room in Kentucky where Mr. McConnell was speaking, his aides appeared flustered by the senator’s abrupt spell.

“I’m sorry, you all, we’re going to need a minute,” an aide told the assembled reporters as the senator stood mute and motionless. She conferred briefly with Mr. McConnell and a man who appeared to be a member of his security detail, who asked him if he wanted to step outside.

Mr. McConnell seemed to resist efforts to be led away, saying he was “OK” and staying briefly to try to answer more questions from the media. But his speaking appeared labored and slightly slurred, and he was guided elsewhere within minutes.

Last month after freezing up in the Capitol, he quickly returned to his news conference and carried on with his regular schedule for the day. He attempted to play down any concerns about his health or his ability to lead the Republican conference in the Senate.