Sen. Chris Murphy, D-Conn., was hospitalized Saturday after a stroke, a spokesperson for the senator said Sunday.

The senator “started experiencing numbness in his arm while at his son’s hockey game,” Allison Herwitt, Murphy’s chief of staff, said in a statement.

“He was taken to a local hospital, where it was discovered he had experienced a stroke,” she added. “He was transferred to Johns Hopkins for further monitoring and is responding well to treatment. The doctors are encouraged by his progress, he is awake and alert, and we are optimistic he will make a full recovery.”

Murphy, 53, is not up for re-election this year but has traversed the country on behalf of Democratic candidates running for elected office.

The senator was slated to be in New Hampshire today, campaigning alongside Rep. Chris Pappas, the Democratic nominee for Senate there.

Murphy is an outspoken critic of President Donald Trump and on Thursday spoke at an event in Washington for the Middle East Institute, where he called the president’s plan to potentially resume the war with Iran after the midterms “insane.”

Earlier this fall, Murphy was one of over a dozen lawmakers whose offices received letters containing suspicious substances.