A spokesman for Reid, a Nevada Democrat, denied there was ever such a deal.
Coleman's allegations are the latest ding against Reid this week. The majority leader had to back off his earlier statement that the Democratic caucus would not seat Roland Burris, a Democrat who had been appointed to fill President-elect Barack Obama's seat by Illinois Gov. Rod Blagojevich.
Coleman, a Minnesota Republican whose term ended Saturday, is contesting his recent 225-vote recount loss to Democrat Al Franken. The election court case could drag on for months.
In a telephone interview with The Associated Press, Coleman said that Reid had initially agreed to let his staffers take 60 days from the end of his term to wrap up 400 open cases. Normally, Senate offices use the two months between Election Day and the end of the term to wrap up cases, but there was no clear winner in the Minnesota race.
"There are people - this is real-life stuff - who come to us for help," Coleman said of the open cases. "They're being hurt by Harry Reid."
"It wouldn't surprise me that he thinks this is a way to put pressure on me to concede, but this is out of bounds," he added. "Harry Reid unfortunately plays a bitter, partisan game. It's vindictive. And it violates what we had understood - there had been a good faith agreement to move this thing forward."
According to Coleman, Reid had agreed to let the staffers work under the direction of the secretary of the Senate, but backed out of the deal this week. The staffers would not have been under Coleman's direction, the former senator stressed.
Reid spokesman Jim Manley said in an e-mail that there couldn't have been such a deal in place, "as the Senate cannot allow staff to do constituent work if they are not under the supervision of a senator, and Norm Coleman is no longer a senator."
Coleman said the open cases include things like Social Security benefits, problems with the Internal Revenue Service, and veterans issues.
Coleman said his staff couldn't simply shift the cases to the state's other senator, Democrat Amy Klobuchar - both because permission was needed from the constituents, and because many of the cases are too involved to hand over midstream.
"We're not looking to take on new cases," Coleman said. "We just want to finalize the cases we've been asked to work on. This is not a big ask."
Coleman said he's kept quiet about the issue until now, hoping it could be resolved through negotiations.
"Maybe folks will understand why they haven't heard from my office," he said. "People deserve to understand that we haven't walked away from them."
A spokesman for Senate Republican leader Mitch McConnell of Kentucky, Josh Holmes, said that his staff hopes to talk with Reid to resolve the issue.
(Copyright 2009 by The Associated Press. All Rights Reserved.)