Sen. Tim Johnson (D-S.D.) turned 60 yesterday, two weeks after emergency surgery to repair a brain hemorrhage that has left him in critical condition.

Julianne Fisher, a spokeswoman for the senator, said Johnson will not be present in the first days of the new Congress next week but is continuing to improve. She said he is responsive to directions from his wife but has not yet spoken.

It is too soon to tell how long recovery will take, Fisher said.

In a statement yesterday, Johnson's doctors said he remains in intensive care at George Washington University Hospital. They have released few new details about Johnson's condition and prognosis since the days after the Dec. 13 surgery to stop bleeding in his brain.

Vivek Deshmukh, head of Johnson's surgical team, said in a statement that the senator's overall condition has improved and that he is gradually being weaned off sedation to help his brain heal.

Johnson's wife, Barbara, said that her husband "continues to give us great hope" and that two of the couple's three grown children were at the hospital on his birthday.

Johnson was diagnosed with arteriovenous malformation, a condition that causes arteries and veins to grow abnormally large, become tangled and sometimes burst. He was rushed to the hospital after becoming disoriented during a call with reporters.

His illness raised questions about the Democrats' one-vote majority in the upcoming Senate session. Should Johnson's seat become vacant, South Dakota Gov. Mike Rounds, a Republican, could replace him with a Republican.

A Republican appointee would create a 50-50 tie and effectively allow the GOP to retain Senate control because of Vice President Cheney's tie-breaking vote. But there is precedent for senators to continue to hold office while incapacitated.