Senator Chris Murphy, a fierce Trump critic who is not up for re-election in the midterms, is ‘alert’ after a stroke.

United States Senator Chris Murphy, a high-ranking Democratic legislator, has suffered a stroke but is “awake and alert”, his senior aide said.

Murphy remained hospitalised on Sunday after seeking medical care for numbness in his arm the day before, his chief-of-staff, Allison Herwitt, said in a statement.

She said he was “responding well to treatment” at John Hopkins, one of the country’s top hospitals.

“The doctors are encouraged by his progress, he is awake and alert, and we are optimistic he will make a full recovery,” Herwitt said.

Murphy is not up for re-election in Tuesday’s midterms that will decide which party controls Congress, but is considered a potential presidential candidate in 2028.

A 20-year senator from the state of Connecticut, Murphy serves as a top Democrat on two powerful Senate committees: appropriations, which decides how US government funds are allocated, and foreign relations.

Murphy toured the Middle East in October, the first regional trip by a US Democrat since the US-Israel war on Iran began in February.

He has been a fierce critic of US President Donald Trump and the Iran war, pledging that Democrats will withhold funding for the war if they win the Senate on Tuesday.

He accused the US Defense Department of denying him access to a US military base in Qatar during his trip last month and has pledged to investigate Trump and his family for alleged corruption if Democrats win the Senate.

Trump said he was “really surprised” to learn about Murphy’s stroke, adding that “nobody wants to have that”.