BOEING and the machinists’ union have negotiated a new contract proposal that would provide bigger pay rises and bonuses in a bid to end a strike that has stopped aircraft production for more than a month.

Announcing the possible deal on Saturday, the International Association of Machinists and Aerospace Workers (IAM) said it planned to hold a ratification vote on Wednesday.

The union said the Boeing offer would increase pay by 35 per cent over four years, up from the 30 per cent that the company offered last month. 

It also raises the ratification bonus to $7,000 per worker (£5,000) from $6,000 (£4,500).

The new offer would not restore a traditional pension scheme, a key demand of the 33,000 striking workers, but it would increase the amount of contributions to retirement plans that Boeing would match. 

It would also retain performance bonuses that bosses wanted to eliminate and make them at least 4 per cent of pay, the union said.

“The fact the company has put forward an improved proposal is a testament to the resolve and dedication of the front-line workers who’ve been on strike and to the strong support they have received from so many,” union district presidents Jon Holden and Brandon Bryant said in a statement.

Boeing said: “We look forward to our employees voting on the negotiated proposal.”

The union credited acting Labour Secretary Julie Su for helping produce the new proposal. 

Ms Su met with company and union officials in Seattle last week, in an indication of the White House’s concern at the strike’s impact on the economy.

The union said some details, including when workers would return to their jobs if they approve the deal, will be put to members in Wednesday’s vote.

About 33,000 IAM members began striking on September 13 after more than 94 per cent had voted to reject an earlier Boeing offer.