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“If the parties were to change tomorrow, their positions on the issue would change,” he said. “It’s quite amazing how quickly they can change [positions] on those issues.”

Then-Senate Majority Leader Robert C. Byrd, West Virginia Democrat, holds the record for shepherding the longest legislative day in the chamber, which began on Jan. 3, 1980, and lasted for 162 calendar days.

Mr. Reid said Wednesday he was “cautiously optimistic” that he will be able to reach bipartisan deal on filibuster reforms. But, if not, he suggested he wouldn’t hesitate to force a simple majority vote on the issue.

The filibuster — which has a long history in the Senate, but which doesn’t exist in the House — is a procedural move used to stall or block bills or nominees and requires at least 60 votes to overcome — a near-impossible scenario with the Democratic caucus’ slim majority since 2009.

Democrats have accused Senate Minority Leader Mitch McConnell of abusing the rule, saying he has used it so excessively it has mired the chamber in historic gridlock. The Kentucky Republican has countered he is left with no choice because Mr. Reid often refuses to allow many — or any — Republican amendments to legislation.

• Stephen Dinan contributed to this article.