For one senator, age was a contributing factor in his decision to retire in 2010. Having watched former West Virginia Sen. Robert Byrd’s health deteriorating during his final years in the Senate, this lawmaker had a hard time envisioning that type of life for himself.

“In the last two years, with the Parkinson’s [disease] and everything, it was sad,” said the retiring senator, who asked for anonymity so that he could speak candidly about the sensitive issue of his colleague’s age. “They’d haul him out and he didn’t even know he was there … and God, I know that’s not what the Senate is about.”…

The senators who voluntarily addressed the issue said there are many capable, sharp, and active upperclassmen who will run for re-election. The problem isn’t necessarily about their mental and physical ability at the time of the campaign, they noted. It’s more a question of how those abilities can hold up over the next six years of their term in office.

“A lot of people run for re-election when they’re 80 and they feel perfectly fine, they’re in great health,” said historian Ritchie, “but it’s a long time, six years, while you’re there. And they get ill [or] something happens.”