Washington (CNN) -- Democratic Sen. Ron Wyden of Oregon said Thursday he will undergo surgery next week for early stage prostate cancer.
Wyden, 61, said he was diagnosed with the disease after his annual physical examination in November, and scheduled the surgery for Monday in the belief that the Senate would be on its holiday recess.
Instead, the Senate is likely to still be in session next week, facing possible votes on a new nuclear arms treaty with Russia, repeal of the "don't ask, don't tell" policy bar openly gay and lesbian soldiers from the military, a measure authorizing government spending for the rest of the fiscal year and other issues.
"It now appears that I will be missing votes tomorrow (Friday) and possibly next week while I prepare and undergo this procedure," Wyden said in a statement. "I expect to be back to work full-time when the Senate reconvenes in January."
The surgery will take place at Johns Hopkins Hospital in Baltimore, Maryland.
Without Wyden, Senate Democrats will see their caucus decreased to 57 votes, three short of the 60 needed to overcome expected Republican filibusters of the upcoming measures.
CNN's Ted Barrett contributed to this report.