Democratic Unionist chief Arlene Foster and Sinn Féin's Stormont leader Michelle O'Neill have been urged to set aside their differences and travel to Washington together to lobby for jobs at Bombardier's Northern Ireland factory.
Uncertainty hangs over jobs at the aircraft manufacturer's Belfast site amid a trade dispute between Bombardier and rivals Boeing.
In September, the US Department of Commence announced its intentions to impose trade tariffs of 220 per cent on Canadian-based Bombardier's C Series jets, after Boeing claimed the firm had received excessive government support which gave an unfair business advantage in breach of trading regulations.
In October, a further 80 per cent tariff was proposed, raising concerns that job cuts could follow at the Belfast site.
In an evidence session of the Northern Ireland Affairs Committee at Westminster, representatives from trade union Unite, which represents many Bombardier employees, told MPs that despite the powersharing crisis at Stormont, Ms Foster and Ms O'Neill should travel to the US to lobby on behalf of workers.
George Burnside, a senior lay representative for the union, told MPs: "We feel let down that none of the representatives from the DUP or Sinn Féin have gone to Washington. The main parties should be in Washington, on Capitol Hill, rapping doors.
"They seem more interested in language and flags, and everything else is going down the tubes. It's a serious situation."
He added: "I know there's obviously not a powersharing government in Northern Ireland, but I think it would be helpful if maybe someone out of this committee, the Defence Secretary and Arlene and Michelle would go to America themselves, at least it should be seen that the Northern Ireland Affairs Committee is doing something, the two main Northern Ireland parties are doing something."
Responding, Lady Sylvia Hermon, an independent unionist MP on the committee, suggested it could write to Ms Foster and Ms O'Neill to ask them to attend as "Acting First Minister and Acting Deputy First Minister".
Lady Hermon said: "I have to say I'm shocked that they have not already been to Washington but it might be helpful if we were to write and ask them to go as a matter of urgency.
"If they were to go together, that would send out such a powerful message. That's what we need. It's not about how they vote, it's about saving jobs in Northern Ireland, and they should be standing shoulder to shoulder to save those jobs. It's obvious."
Northern Ireland has been without an executive at Stormont since January, when powersharing between the DUP and Sinn Fein collapsed.
Since then, there have been numerous rounds of negotiations with a view to returning to government but no deal has been reached. The parties remain at odds over a number of issues related to language and cultural issues.
Ms O'Neill and Ms Foster attended separate meetings at 10 Downing Street with Theresa May on Tuesday, where the prime minister urged them to continue working to reach an agreement.
A final ruling on whether tariffs will be imposed on Bombardier is expected in the new year.
