(adds details from doctors) By Richard Cowan WASHINGTON, Dec 15 (Reuters) - U.S. Sen. Tim Johnson continued to improve after brain surgery this week, heartening fellow Democrats who were optimistic on Friday that he will be able to remain in the Senate. "His most recent CT scan shows that the pressure has been relieved from his brain and there is no further bleeding," neurosurgeon Vivek Deshmukh said in a statement. "Currently his brain pressures are normal." Doctors also said Johnson will remain hospitalized until his brain swelling subsides and that he will need physical therapy for weakness on the right side of his body. Johnson's emergency hospitalization on Wednesday raised concerns on Capitol Hill about his ability to continue in the Senate when the 110th Congress convenes on Jan. 4 -- as well as Democrats' chances of controlling the Senate. The Democrats narrowly won an advantage in the Senate in November elections. But if Johnson has to leave the Senate, South Dakota Gov. Michael Rounds likely would appoint a fellow Republican to fill the last two years of Johnson's term. That could give Republicans control of an evenly split Senate since Republican Vice President Dick Cheney can cast tie-breaking votes. Former South Dakota Sen. Thomas Daschle, who led Senate Democrats for several years before his 2004 defeat, visited Johnson on Friday. DASCHLE UPBEAT Daschle told reporters Johnson was "doing quite well" and gave an upbeat assessment of his future. "I fully expect him to be back in the saddle and working and voting and conducting his public life," Daschle said. Johnson, who will turn 60 on Dec. 28, was taken to George Washington University Hospital on Wednesday and had brain surgery to stop dangerous bleeding that caused speech problems earlier that day. Doctors have not ruled out the possibility of additional surgery to deal with a brain malformation that he probably had since birth. Another member of Johnson's surgical team, Dr. Anthony Caputy, said patients with an intracranial hemorrhage routinely experience post-operative swelling of the brain. "Much like a bruise, it takes time to heal," he said. The medical team's latest public assessment continued to be cautious. "Considering his initial presentation, his progress is encouraging," Caputy said. "He is now stabilized and continues to show signs of responsiveness to the medical staff and the family." President George W. Bush's press secretary, Tony Snow, said no one from the White House had contacted Rounds about the situation. "This is a time to pray for Tim Johnson's health," Snow said. "And I'll leave it to others to start doing political calculations." In elections last month, Democrats wrested control of the U.S. House of Representatives and Senate from Republicans, promising to challenge Bush's agenda in the last two years of his presidency. When the Senate convenes in January, Republicans and Democrats will have to agree on rules for running committees and other functions of the 100-member chamber in case of a change in the political makeup resulting in a 50-50 split.(additional reporting by Susan Cornwell)
