For the second time in just over a month, Senate Republican leader Mitch McConnell appeared to freeze while speaking to reporters.
At a press event in Covington, Kentucky, the 81-year-old paused for more than 30 seconds when asked whether he would run for-re-election in 2026.
Aides attempted to prompt the senator, but it took several more seconds for Mr McConnell to recover.
He then answered two more questions, which had to be repeated by staff.
He made no comments about his health, before leaving with aides.
“Leader McConnell felt momentarily lightheaded and paused during his press conference today,” a spokesperson said after the incident.
Mr McConnell’s first verbal lapse occurred during a press conference at the US Capitol in Washington DC on 26 July.
There, he paused mid-sentence for approximately 20 seconds, before being ushered away by his fellow Republican senators.
He later returned and told reporters he was “fine” and had felt “lightheaded”.
Mr McConnell, who leads the Republican party’s narrow minority in the upper chamber of Congress, was admitted to hospital for a week after suffering a concussion and a fractured rib following a fall outside a Washington area hotel in March.
He was transferred to a rehabilitation facility and did not return to the Senate until mid-April.
After the freezing incident in July, US media reported that Mr McConnell has endured at least three other falls since February.
This latest episode will again raise questions about the health of the Kentucky senator heading into what will be a busy autumn legislative session, as Congress attempts to avoid a partial government shutdown at the end of October.
An aide to Senator John Thune, Mr McConnell’s deputy in the chamber, told reporters they had spoken after the incident. Mr McConnell “sounded like his usual self and was in good spirits”, Ryan Wrasse said.
“We have disagreements politically but he’s a good friend and so I’m going to try and get in touch with him later this afternoon,” President Joe Biden said later on Wednesday.
Concern over Mr McConnell’s health follows questions about the condition of 90-year-old California Democratic Senator Dianne Feinstein, who was absent from the chamber for months after being diagnosed with a severe case of shingles.
The average age for members of the US Senate is 65.