Senator Tim Johnson, making a widely watched recovery from brain surgery, looked significantly better on Friday, his party’s U.S. Senate leader said after visiting him in the hospital.

Family and colleagues have been encouraged by the South Dakota Democrat’s progress, yet doctors said it was too early to say whether further surgery would be required.

Johnson suffered a brain hemorrhage Wednesday that was caused by a rare and sometimes fatal condition. His illness came just weeks before Democrats are to take control of the Senate by the slimmest of margins.

Harry Reid of Nevada, who is to become majority leader when the new Senate convenes January 4, has visited Johnson at the hospital each day since the incident. After stopping by for a half hour Friday, Reid told reporters Johnson looked good, but declined to say more about his condition.

Johnson, 59, was in critical condition at George Washington University Hospital but was described as recovering on Thursday. The U.S. Capitol physician called his condition “an uncomplicated postoperative course” Friday after visiting with him.

Johnson was responding to the voice of his wife, Barbara, and following directions after the surgery, the senator’s office said in a statement.

Democrats are preparing to take control of the Senate with a 51-49 majority when Congress convenes in three weeks. Democrats seized control of both the House and Senate from Republicans in the November 7 midterm elections.

Aside from the fact that this is a man fighting for his life, there’s the political sticking point. If a senator leaves office, a replacement is named by that state’s governor. In this particular case, that’s South Dakota Republican Mike Rounds, who would likely name a member of his own party and thus create a 50-50 tie in the Senate.

Because of Vice President Dick Cheney’s tie-breaking vote, that would in essence throw the Senate back into Republican hands.

Johnson’s symptoms first surfaced during a telephone conference call with reporters on Wednesday, CBS News reports. In the middle of a question, Johnson began to falter, and was soon diagnosed with an arteriovenous malformation in his brain, a condition he’s probably had since birth.

The arteries and veins were knotted together like a ball of yarn. As the tangle grew, one of the blood vessels apparently burst. Doctors stopped bleeding in Johnson’s brain and drained the blood that had accumulated there. On Thursday, Johnson underwent an additional procedure to prevent further blood clots.

“We’re all praying for a full recovery,” Reid said Thursday. “We’re confident that will be the case.”

But will he be able to go back to work, and when?

“Historically, senators in both parties have given a lot of leeway to people with illnesses like this,” CBS News’ Bob Schieffer said. “When [Delaware Senator Joe] Biden had surgery in 1988, for example, no one questioned he was going to be off the job for several months.”

“They waited until he was able to come back and he recovered completely. I think you will see something like that. There will be no push to force him to resign or something like that.”

The White House offered best wishes.

“Look, he’s a great guy,” White House Press Secretary Tony Snow said, “and it’s one of these things where everybody’s concerned and our thoughts and prayers are with him, his family, his staff, his colleagues.”