WALNUT CREEK (CBS SF) – Rep. Mark DeSaulnier, a Democrat who represents the East Bay in Congress and has been hospitalized after falling and fracturing a rib during a recent run, has suffered a serious downturn in his condition, according to his chief of staff.

Chief Of Staff Betsy Arnold Marr tweeted Saturday that DeSaulnier — who was in stable, but serious condition — has now been downgraded to critical condition.

READ MORE: Unique Twist To Pandemic Shutdown Of Long-Establish Santa Clara Restaurant

“The doctors are doing everything they can to care for the congressman,” she posted. “Mark’s family and staff appreciate your thoughts and prayers during this very difficult time.”

Mark DeSaulnier

Mark DeSaulnier (D-Concord)

READ MORE: Man Found Dead In Bullet-Riddled Vehicle In Union City

DeSaulnier was admitted to a Washington, DC-area hospital more than a week ago to treat complications from pneumonia after suffering a “traumatic rib fracture” when he fell.

He initially was listed as in serious, but stable condition but over the last 48 hours his condition has deteriorated. He had been tested for COVID-19 and the test came back negative.

DeSaulnier has represented California’s 11th congressional district, which includes most of Contra Costa County, since 2015.

MORE NEWS: SF Restaurant Apologizes for Denying Service to Armed, On-Duty Police Officers

According to the biography on his congressional website, DeSaulnier is described as an avid runner, who has completed 21 marathons.