As Hogan & Hartson and Lovells hurtle toward the biggest trans-Atlantic merger in years, the firms’ top leaders have hit the road in advance of a partnership vote on the deal in mid-December.

News of the Hogan-Lovells engagement broke on Oct. 8, and plans call for a merged firm to make it to the altar on May 1 — a scant six months from now. Both firms have declined to comment publicly on details that have leaked out about the proposed structure for the merged firm.

Both Hogan & Hartson Chairman J. Warren Gorrell Jr. and Lovells managing partner David Harris are making presentations at key offices on both continents even as they hold complicated discussions geared at making key decisions about how the merged firm will be structured.

Gorrell, for instance, has spent much of the past month traveling back and forth to Europe, visiting Hogan and Lovells offices in London; Frankfurt, Germany; Munich, Germany; Berlin; Rome; and Warsaw, Poland. On Nov. 20, Gorrell and seven Hogan partners attended Lovells’ annual partner meeting in Lisbon, Portugal, to provide further details and field questions about practices, compensation and the vision for the merged firm, a source who attended the meeting said.

Joining Gorrell were partners Prentiss Feagles, who co-chairs Hogan’s tax group; Dennis Tracey III, managing partner of Hogan’s U.S. offices; Stephen Immelt, managing partner of its international offices; Jeanne Archibald, who oversees Hogan’s practice management effort; Stuart Stein, who heads the firm’s financial services and corporate governance groups; and Gernod Meinel, managing partner of Hogan’s German offices. Gorrell has said that Germany is a key market for the firm.

At the Lisbon meeting, according to the source who attended, Claudette Christian, a member of Hogan’s executive committee and its chief diversity officer, was introduced as Hogan’s pick to join Lovells’ John Young as co-chairwoman of the new firm. Christian and Young will oversee all of Hogan Lovells’ internal operations for a two-year term, ending on April 30, 2012.

Christian said she couldn’t comment on anything related to the merger.

POSSIBLE CONFLICTS

On the Lovells side, David Harris has made similar presentations in Hogan’s New York and Washington offices.

Harris has been joined by Young; Patrick Sherrington, head of Lovells’ dispute resolution practice; Andrew Skipper, who chairs its corporate practice; David Hudd, chairman of its finance practice; Andreas von Falck, former chairman of its intellectual property practice; Marc Gottridge, managing partner of Lovells’ U.S. offices; and Susan Bright, chairwoman of Lovells’ competition and E.U. law practice.

The two firms have certainly already dealt with some key issues that could derail things, such as conflicts.

“It’s almost always conflicts that determine whether two firms can be combined,” said Michael Pollack, head of global strategy for Reed Smith, which went through a 2007 merger with London-based Richards Butler. British law has a narrower definition of conflicts, but clients don’t have the option to waive them.

Some details of the firm’s structure have leaked out. The firm will have two separate partnerships — one based in the U.S. and one everywhere else — with separate profit pools. Still, sources on both sides of the negotiating table with firsthand knowledge of the talks said that the firm will operate seamlessly across the barrier of the Atlantic.

It would be unprecedented for a merged firm of this size not to have kinks to work out and, while it does, competitors will be moving to position themselves. “We’ll be talking to our clients over the next few years about how often we are seeing Hogan Lovells,” said William Perlstein, co-managing partner of Wilmer Cutler Pickering Hale and Dorr. “If their footprint is being viewed by clients as successful and able to offer better services, it’s going to cause people to consider pursuing similar opportunities.”

Jeff Jeffrey can be contacted at jjeffrey@alm.com.