By Jonathan Kaminsky

OLYMPIA, Wash., Nov 20 (Reuters) - An advertisement placed in The Seattle Times on Wednesday by a group hoping to encourage Washington state to keep up its fight to secure the coveted work on the new Boeing 777 includes a notable miscue.

At the top of the full-page ad, under the all-caps text "The Future of Washington," is pictured not a Boeing jet, but rather an A320 from archrival Airbus.

The ad, which prominently displays the logo of the Washington Aerospace Partnership, a coalition of business, labor and government groups championing the industry, urges state lawmakers to pass a large-scale roads-and-transit tax package that Boeing executives have said would make the state a more desirable venue for future projects.

Airbus officials confirmed the plane depicted in the ad is an A320 but declined further comment.

A spokeswoman for the Seattle Metropolitan Chamber of Commerce, who acknowledged placing the ad on behalf of the Aerospace Partnership in an interview with The Seattle Times, did not return messages seeking comment.

Boeing formally launched the new 777, formerly codenamed 777X, on Sunday with 259 orders worth more than $95 billion at list prices - the largest combined order in the company's history. The jet is due to enter service around 2020.

Earlier this month, the company offered to site work on the new plane in Washington state, where it has a large core of experienced workers, in exchange for tax breaks and a contract extension with its largest union that included significant concessions from labor.

State lawmakers passed $8.7 billion in tax incentives for the company extending until 2040 but members of the International Association of Machinists & Aerospace Workers District 751 last week voted down the proposed contract by a 2-1 margin.

Immediately after the vote, Boeing executives were on planes around the country to meet with officials in states interested in landing the work, which the ill-fated ad refers to as "the biggest job-creating prize in the country since the 1990s."

Boeing Chairman and Chief Executive Jim McNerney told reporters in Dubai on Monday that the company expects to make a decision on where to build the new 777 within 3 months.

"It's too bad that they made that mistake," said David Groves, spokesman for the Washington State Labor Council, an Aerospace Partnership member. "Hopefully it doesn't undermine the good work the Aerospace Partnership is trying to do."