Rising optimism in the Baie Des Iles camp has been mirrored by punters as momentum builds around Katie Walsh's mount in the Grand National.

Walsh will be teaming up with her husband, trainer Ross O'Sullivan, and is confident the seven-year-old mare can give a bold account in the Aintree spectacular on Saturday.

Walsh, who finished third aboard Seabass in 2012, is bidding to become the first woman to ride the winner of the world's most famous jumps race.

Bryony Frost and Rachael Blackmore also targeting the same accolade aboard Milansbar and Alpha Des Obeaux respectively.

Baie Des Iles has been backed from 50-1 to 20-1 since Monday.

"There is so much luck involved in a Grand National. It can depend on where you've been positioned throughout the race or whether you're behind a horse who doesn't jump well. There are a lot of variables involved," Walsh said.

"Every runner has a chance of winning the Grand National. You just do not know what is going to happen.

"We're really excited about Baie Des Iles and it will be great to be a part of the race again."

Walsh's mount was a creditable third in the Grand National Trial at Punchestown in February on heavy ground and conditions at Aintree are not expected to pose a problem.

"She has plenty of form on heavy ground, but she has a good action and I think better ground wouldn't be too much of an issue, either," Walsh said.