The US Senate Republican leader Mitch McConnell appeared to freeze for more than 30 seconds during a public appearance, weeks after a similar incident sparked concern for his health.
When asked if he would run for re-election on Wednesday, the 81-year-old Kentucky Republican stopped and stared, before being asked: "Did you hear the question, senator?"
Mr McConnell continued to be unresponsive before coming round and briefly responding to another question.
It comes after the senator froze mid-sentence and stared vacantly for about 20 seconds during a press conference in July.
After refocusing, Mr McConnell brushed off a question he was asked about former President Donald Trump - another that had to be repeated to him - and left the conference.
A spokesperson for the senator said that he had "felt momentarily light-headed" before the conference in Kentucky, and he will be consulting a doctor prior to the next public event.
Last month, Mr McConnell froze after approaching the podium for his weekly press conference and speaking about the annual defence funding bill, he appeared to lose his train of thought and trailing off with a drawn-out "uh".
Questions were being asked about the state of Mr McConnell's health after his speech has become more halting and his walk slower than usual.
He has been seen using a wheelchair on his commutes to and from Kentucky
In March, Mr McConnell did not return to the Senate for six weeks after suffering from concussion and a broken rib after falling and hitting his head at an event.
He also needed surgery after a separate incident when he fell in his home and fractured his shoulder.
As a child, Mr McConnell had polio, and he has long acknowledged some difficulty as an adult in climbing stairs.
First elected to the Senate in 1984, and as Republican leader since 2007, Mr McConnell's current term runs until 2026.