US senator John Fetterman, who suffered a stroke during his election campaign last year, was hospitalised after feeling lightheaded while attending a Senate Democratic event, his office said.

Fetterman’s communications director, Joe Calvello, said in a statement issued on Wednesday night: “Towards the end of the Senate Democratic retreat today, Senator John Fetterman began feeling lightheaded. He left and called his staff, who picked him up and drove him to the George Washington university hospital.”

Initial tests at the hospital did not show evidence of a new stroke, Calvello said, but doctors were running more tests and the senator would remain in hospital overnight.

“He is in good spirits and talking with his staff and family. We will provide more information when we have it,” Calvello said.

Fetterman overturned Pennsylvania’s Republican-held Senate seat in last year’s midterm elections, his victory helping to ensure that the Democrats kept control of the US upper house.

Fetterman suffered a stroke in May last year which affected his ability to speak and process the sound of others’ speech. He fought a close campaign against Republican Mehmet Oz – a celebrity doctor – much of which was dominated by questions about Fetterman’s health.

After his stroke, during which Fetterman said he “​​almost died”, the Oz campaign launched a number of attacks with one Oz aide, Rachel Tripp, claiming Fetterman might not have had a stroke if he “had ever eaten a vegetable in his life”.

After leading in the polls for much of the year, Fetterman saw the race tighten in the closing weeks of the campaign after a disappointing debate performance which saw some question his ability to govern.

During his victory speech in November, Fetterman referred to the stroke and how it had shaped his political priorities.

He referred the stroke again as he spoke about what he hoped to achieve in the Senate. “Healthcare is a fundamental human right,” he said. “It saved my life and it should all be there for you whenever you might need it.”