GM's Mary Barra, Mark Reuss returns to negotiating table with UAW

The meeting came about 14 hours after the UAW sent a letter to the National GM Council convening trade union local officers to Detroit on Thursday for a morning meeting at downtown Marriott.

More: The UAW convenes the National GM Council for Detroit, but has no agreement yet

More: Here is what has been decided and what remains at stake in the GM-UAW talks

Tuesday's meeting between Barra and the top-level UAW leaders could signal that GM and the UAW are close to reaching a tentative deal, Harley Shaiken said, a professor at the University of California, Berkeley who specializes in labor.

"They probably have a frame, and they have to iron it out," Shaiken said. "As always, it's not done until it's done. But this is clearly a promising development, and the timeframe will work to present a tentative agreement for UAW's GM Council on Thursday."

GM executives likely want to liquidate a The union members have shown solidarity to stay on the line and not admit, so that a strike can go further, Shaiken said.

If a tentative agreement is not reached by Thursday morning's meeting, the council can voting shift from ratifying a tentative agreement with something more sinister, he said.

"If we do not have a tentative agreement today or tomorrow, the council will come in to ensure members will endure a longer strike," he said. Shaiken. "GM may have a lot of money on hand, but having cash versus using it on strike – that's not how investors want the money spent."

Thursday's council meeting was billed as an update for the 175 council members on the status of the negotiations. The Council's approval of a tentative agreement is necessary before it could be submitted for ratification.

GM declined to comment on this letter other than to say: "Talks continue."

Notice of the local leaders at this point in the Negotiations is unusual, but something to take seriously, Shaiken said.

Early Monday, three main sticks remained between the two sides that the UAW strike against GM is approaching a month since 46,000 union workers entered strike at 55 GM plants across the country.

The three cases centered on shortening the time for progressive workers, those hired after 2007, to get a higher salary, improve pensions and 401 (k) formulas and for GM to ensure future product will be built in US plants.

Prior to being named GM president in January, Reuss served as the company's global leader in product development. With product allocation as a top agenda issue for UAW, bringing Reuss in the talks can signal high-level work to address these issues.