WASHINGTON (Reuters) - Senate Majority Leader Harry Reid said on Sunday that Democrats and Republicans still had key differences in talks to avert a looming year-end "fiscal cliff," and he had not been able to make a counteroffer to the latest Republican proposal.

"I've had a number of conversations with the president and at this stage we're not able to make a counteroffer," Reid said on the Senate floor.

He said that as the day wears on, Democrats may be able to make such an offer.

"I think that the Republican leader has shown absolutely good faith. It's just that we're apart on some pretty big issues," Reid added. (Reporting By David Lawder; Editing by David Brunnstrom)