Story highlights Sen. Thad Cochran has had health problems that kept him out of office this fall

Sen. John McCain is fighting brain cancer, a diagnosis he announced this summer

Washington (CNN) Republican leaders in the Senate are keeping a close eye on the health conditions of two senior members -- John McCain of Arizona and Thad Cochran of Mississippi -- ahead of a crucial vote on the GOP tax plan next week.

Both have missed votes this week, though party leaders expect the two senators to be in position to vote for the tax bill, which could happen as early as Monday.

McCain, who announced he had brain cancer this summer , was hospitalized this week "for normal side effects of his ongoing cancer therapy," his office said in a statement Wednesday night.

"Senator McCain looks forward to returning to work as soon as possible," the statement said, though it did not include any details on the timing of his return.

Cochran had "an outpatient procedure Monday afternoon to address a non-Melanoma lesion on his nose," his spokesman Chris Gallegos told CNN. "The procedure was more extensive than expected, but the senator is doing well and available now for votes if needed."

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