Senate Majority Leader Harry Reid was hospitalized Friday after complaining earlier in the morning that he was "not feeling well," his aides told reporters.
After conducting tests, doctors found no immediate medical problems with the 74-year-old Democrat from Nevada, but he will remain in the hospital for observation and will not be in the Capitol as the Senate wraps up its final day of legislative work for the year.
Reid's spokesman said the Senate's No. 1 Democrat "is alert, resting and feeling better."
In August 2005, Reid discovered he had suffered a mild stroke after going to a doctor to report feeling unwell.
Reid, a former amateur boxer, has been serving in Congress since 1983 and in the Senate since 1987. He's serving his fifth Senate term.
Reid has been working late hours in an effort to come to an accord with Republicans over the confirmation of a half-dozen executive branch nominees.