(Reuters) -About 3,000 striking workers at RTX's Pratt & Whitney are slated to vote on a contract offer from the engine maker next week, the company and the union representing the workers announced on Friday, one day after negotiations resumed.

The nearly three-week-long strike has significantly slowed production at two of the company's plants in Connecticut.

Union representatives have said the workers' top priority is getting Pratt to commit to keep work for Lockheed Martin's F-35 fighters in the state. Members of the International Association of Machinists and Aerospace Workers overwhelmingly rejected the first contract offer on May 4. 

"On Tuesday, our members will decide if we achieved our objectives around job security, wage security, and retirement security," IAM leaders said in a message sent Friday to members. "This new proposal has significant changes/improvements in all three of these core areas."

A Pratt spokesperson declined to comment on the specifics of the offer. 

The strike is the first in more than 20 years at the enginemaker's Connecticut sites, where it produces engines for the F-35 and about 70% of the company's geared turbofan engine, which is used in European planemaker Airbus' strong-selling A320 neo family.

Pratt has reassigned some engineers to production lines as part of its contingency plan, which was first reported by Reuters.