Senate Minority Leader Mitch McConnell pointedly raised the prospect of a stalled lame-duck session if Democratic leaders keep threatening to change the rules at the start of the new Congress during the final weeks of the old one.

“We have huge issues before us here at the end of the year, much of which will probably carry over into next year,” McConnell said. “It’s a time that we ought to be building collegiality and relationships and not making incendiary moves that are damaging to the institution and could have serious ramifications on our ability to work together here at the end of the year.”

The irate comment from the Kentucky Republican came while trading barbs Monday with Senate Majority Leader Harry Reid, D-Nev., after a lengthy floor speech about chamber operations. Reid reiterated his plan to change the rules by a simple-majority vote at the start of the next Congress in an effort to make legislation move somewhat more quickly through the chamber.

In responding to McConnell, Reid invoked the name of a Senate legend, the late Robert C. Byrd of West Virginia.

“I would suggest to everybody here, Sen. Byrd wouldn’t like what’s going on here, and he would work with us to get these rules changed,” Reid said on the floor.

“The filibuster is not part of the Constitution; it’s something we developed here to help get legislation passed,” Reid said. “Now, it’s being used to stop legislation from passing.

“We’re going to continue moving forward to make the Senate more efficient. Does that mean it will be really efficient? No, because we’re changing one aspect of the filibuster rule.”

The back-and-forth between McConnell and Reid shows how much every action and word in the Senate can have unexpected repercussions — even a threat of modifying the rules could hamper work on year-end business to avert scheduled spending cuts and tax increases.

The Senate has long been mired in a seemingly endless cycle of obstruction, disagreement and delay — for which Democrats and Republicans trade blame.

“I had hoped going into the lame-duck session we’d have an entirely different view of how to bring this place together and to begin to solve the problems,” McConnell said. “It’s a sad day for the Senate, and we will go forward as best we can under this extraordinary set of circumstances.”

Both party leaders fashion themselves as students of the Senate and defenders of the chamber’s prerogatives. In 2006, McConnell pushed a resolution through the Senate ensuring that Kentucky’s senior senator has the desk of 19th-century legislator Henry Clay.

As Reid sought to downplay the significance of the changes he supports on day-to-day work, his Republican sparring partner went to the other extreme, warning against the precedent-setting move to make changes with a simple-majority vote at the start of a new Congress using a procedural move known as the “constitutional option.”

Opponents of that move argue that the Senate is a “continuing body” because only one-third of the Senate is chosen in any given election, so rules of procedure carry over from Congress to Congress.

McConnell called the simple-majority maneuver, championed by a collection of mostly newer Democratic senators, a move “to break the rules to change the rules.”

Vice President Richard Nixon, as president of the Senate in 1957, advised that he believed one Congress could not be formally bound to the rules of a previous Congress.

Reid and other Democrats increasingly argue that Republican obstruction has forced the dramatic increase in filing of cloture petitions to limit debate.

Incoming Democratic senators are much more willing to change the rules with a simple-majority vote than some of their veteran and departed counterparts. For example, Sen. Richard Blumenthal, D-Conn., advocated for changes after the exchange between the leaders on Monday.

“From the very first days that I have been a member of this body, I have strongly believed that the filibuster needs to be ended or at least greatly modified so as to permit the business of this great chamber to go forward, and I believe that the new members who have come here have heard that message loud and clear from the American people,” he said.

That view stands in contrast to the man Blumenthal replaced, Democrat Christopher J. Dodd, who spent 36 years in Congress and used his farewell speech to caution against haste in rules changes.

“I can understand the temptation to change the rules that make the Senate so unique — and, simultaneously, so frustrating,” Dodd said in 2010. “But whether such a temptation is motivated by a noble desire to speed up the legislative process, or by pure political expedience, I believe such changes would be unwise.”

Alan K. Ota contributed to this report.