The potential combination between global megafirm Dentons and Atlanta’s McKenna Long & Aldridge has hit a snag, according to a McKenna partner.

The internal deadline for McKenna’s equity partners to cast their votes on the merger was noon Friday, the partner said, but McKenna’s chairman, Jeffrey Haidet, sent an email to the partners that morning to announce that the vote had been postponed.

Haidet’s email said that some partners wanted more information on the deal before making a decision, according to the partner in McKenna’s Washington office who asked not to be identified.

Dentons said Friday in an emailed statement that it was too soon to comment on the voting: “When the leadership of Dentons and McKenna Long & Aldridge LLP announced their recommendation, we stated that the voting period will end no later than November 14, 2013. It would be premature to share information until all partnership entities of both firms have concluded their voting.”

Haidet did not respond to requests for comment, but McKenna sent an email late Friday afternoon similar to that of Dentons.

The boards of both Dentons and McKenna recommended to their partners that the firms combine, subject to the approval of their respective partnerships, the two firms said in a joint statement on Oct. 29. The voting by the partnerships would be completed by Nov. 14, the statement said.

A supermajority of two-thirds of the McKenna partners must vote in favor of the combination for it to go through. The McKenna partner speculated that as the noon deadline approached on Friday, the merger vote had not gained the requisite super­majority.

The firm had 97 equity partners and 274 total partners in 2012, according to the Am Law 100 survey. Dentons has 944 global partners, according to its Chambers and Partners report.

McKenna held a town hall meeting on Nov. 6 for the partners to discuss the potential combination, the partner said. The meeting, conducted via video to link in McKenna’s various offices, lasted three to four hours, the partner said, and partners expressed strong opinions both for and against combining with Dentons.

It would create the third-largest firm in the world, with about 3,175 lawyers and professionals, after DLA Piper and Baker & McKenzie, which both have more than 4,000 lawyers. McKenna has about 575 lawyers and professionals and Dentons has 2,600.

Opposition to the merger seemed based in the firm’s Washington office, according to the partner. It was not over any specific deal points but rather because some partners did not see the benefit of combining at all.

McKenna has 13 U.S. offices, plus outposts in Brussels and Seoul, and Dentons has about 75 locations in more than 50 countries. Dentons was created in March from the triple merger of international firms SNR Denton and Salans and Canadian firm Fraser Milner Casgrain.

SNR Denton was itself the product of a 2010 combination between London’s Denton Wilde Sapte and Chicago’s Sonnenschein Nath & Rosenthal.

Dentons is structured as a Swiss verein, with five separate entities under the umbrella of Salans FMC SNR Denton Group, according to its website: Dentons HK, Dentons Canada, Dentons UKMEA, Dentons US and Salans FMC SNR Denton Europe.

The Dentons entities are distinct legally and not financially integrated.

McKenna’s partnership must vote on merging with Denton’s U.S. entity and on joining the verein.