Democrat Sen. Tom Courtney says he isn't certain when he will be back on the Senate floor after undergoing heart bypass surgery in February.

The 65-year-old Courtney earlier speculated he'd return to the Senate on Wednesday, but he told The Associated Press on Tuesday he "miscalculated" his recovery time after his third heart operation on Feb. 28.

Still, he's hopeful of returning later in the week.

When Courtney gets back, he'll give Democrats the 26-24 edge over Republicans that's needed to approve bills on party-line votes.

Until then, Senate Majority Leader Mike Gronstal says he'll fill the debate calendar with "non-controversial bills."

Gronstal says there are plenty of votes that don't require all 26 Democratic votes. On Monday, for example, senators unanimously passed 14 of 15 bills.