Meghan Markle reportedly adding American twist to her wedding as new favorite to design her wedding dress emerges

Meghan Markle’s fairy tale wedding to Prince Harry is now just one month away and the bride-to-be is putting the finishing touches on her wedding day.

Speculation on the biggest guessing game for the big day -- who will design Markle’s wedding gown – is now focused on three designers.

Christopher Bailey, the visionary behind the iconic British brand Burberry, has emerged as the favorite for the coveted assignment.

Bailey, who announced his exit from the company last year, showed his final collection for Burberry at London Fashion Week in February. Some are speculating if his next act could be designing one of the most famous dresses of the decade.

"One of Meghan's closest friends, Markus Anderson, who we saw by her side during the Invictus Games in Toronto, has been seen going into top-secret meetings with Burberry executives here in London just a few days ago," ABC News contributor Omid Scobie shared on "GMA."

Tamara Ralph and Michael Russo, the duo behind the Australian brand Ralph & Russo, are also on the short list.

The fashion house, which designed the jaw-dropping $75,000 gown Markle wore in her engagement photos with Harry, are now declining comment on the royal-to-be.

"Any designer[s] that are doing the dress on the big day will have to have signed a strict non-disclosure agreement," Scobie said. "And with Ralph & Russo, they've actually had to move their external PR company in-house."

He continued, "And that may be one of the biggest clues we've had that they could be one of the dress designers on the big day."

Canadian designer Erdem Moralioglu has also emerged to be a top contender.

Moralioglu is from Canada, where Markle stayed while filming “Suits,” but established his fashion line, ERDEM, in London in 2005.

Designer Roland Mouret, a close friend of Markle's, is among the designers still being discussed by royal watchers to dress Markle in some capacity, or dress her wedding party.

He is now considered by royal watchers to be a more viable choice to design Markle's dress for the intimate, private evening reception at Frogmore House hosted by Prince Charles.

Most insiders think it unlikely Markle will give the nod to a French designer and instead select a British or American designer, or a designer from a Commonwealth country like Canada or Australia.

British designer Victoria Beckham, whose sweater Markle wore in her engagement photos with Harry, recently denied she is creating Markle's dress.

“Sadly, I'm not," Beckham said on "The Late Late Show With James Corden." "But I am sure she will look incredible.”

When Princess Kate wed Prince William in 2011, Sarah Burton, the creative director at McQueen, was asked if she had the commission and denied her involvement.

It was only on Kate's wedding day that Burton finally revealed she was the visionary behind Kate's iconic gown.

As her wedding day approaches, Markle is following a bridal boot camp regime to get ready for her May 19 wedding at Windsor Castle, "GMA" has learned.

Markle, who has said previously that she is a fan of Megaformer pilates, is now focused on cardio work and training with one of Harry's personal trainers at Kensington Palace, according to Scobie.

"Meghan was also recently seen visiting a yoga instructor somewhere here in London, and that will be a big part of her big, bridal body workout," he added.

"GMA" has also learned Markle, a California native, is working with her close friend and style adviser, Jessica Mulroney, to plan an American twist to her wedding celebrations.

"Meghan is actually planning an American-style rehearsal dinner with her nearest and dearest here in London," he said. "That will take place probably without members of the royal family."