Facing a June 1 deadline to restructure,

General Motors

(GM) - Get Report

is heading into two weeks of intense negotiations, with a bankruptcy filing looming.

"We are expecting the restructuring negotiations to intensify this coming week," the United Auto Workers said late Sunday in an email to members. "The UAW is actively involved in these complex negotiations, which involve the Obama auto task force, GM management, bondholders and secured lenders, dealers, part suppliers and other stakeholders."

The UAW says in its email that it "strongly objects to GM's plan to close 16 manufacturing facilities in the United States, while at the same time dramatically increasing the number of vehicles it will be importing from Mexico, Korea, Japan and China for sale in this country."

The plan would result in the loss of 21,000 jobs for UAW members, the union says, and will increase to 23.5% from 15.5% the share of GM's sales in the U.S. market produced in Mexico, Korea, Japan and China.

On the May 11 conference call, GM CEO Fritz Henderson said GM foresees that by 2014 about 7.5% of production for the U.S. market would take place outside of North America. But "this is something we would want to have a discussion with them about," he said. "We have the philosophy of building where we (sell). Not only is that the right thing to do, it's the most profitable thing to do historically."

The automaker has said repeatedly that it does not want to file for bankruptcy protection. But with each conference call, the likelihood appears higher. On the last call, a week ago, Henderson called bankruptcy "more probable," noting, "Certainly, the task we have in front of us is large."

Foremost among GM's challenges is to win an agreement on concessions from bondholders, unlikely given that they number in the thousands. "GM has the issue that there are so many of them, so many more than with

Chrysler

," says Bruce Belzowski, associate director of automotive analysis at the University of Michigan Transportation Research Institute. Chrysler had just 46 bondholders.

However, seeing that Chrysler bondholders are going along with the company's plan in bankruptcy could conceivably influence the GM group, Belzowski says.

Bondholders, who hold billion in notes, are being asked to swap at the rate of 225 shares for every $1,000 of principal. They would then hold about 10% of the company. The Treasury has determined that about 90% of the bondholders need to accept the offer in order to avoid bankruptcy. The deadline is May 26 at 11:59 p.m.

The Ad Hoc Committee of General Motors Bondholders, which holds about 20% of GM's $27 billion in unsecured debt, "continues to pursue a fair and equitable solution, preferably outside of court, and has been participating in ongoing dialogue since announcing our plan," a spokesman said Monday.

GM's dealers also present a problem. The company said Friday it wants to sever ties with 1,100 "underperforming and very small sales volume" dealers. In most cases, existing franchise agreements run through October 2010, the company said.

"I don't think the dealers will say 'OK, fine, no problem,' " Belzowski says. "It seems as though bankruptcy may be the only way GM will be able to handle the dealer issue. This is a once in the lifetime opportunity for the manufacturers, and a once in a lifetime mess for the dealers."

Whatever happens, GM shareholders are unlikely to benefit. Last week, Standard & Poor's reduced its opinion on the shares to strong sell from sell. "We see an increased likelihood that the shares will decline as the company's viability plan deadline approaches," wrote analyst Efraim Levy. Either GM will make a deal to avoid bankruptcy, giving existing shareholders a 1% stake in the company "or, as we think is increasingly likely, GM will file for bankruptcy protection, making existing shares almost worthless."

Shortly after 1 p.m. Monday, GM shares were up 9 cents to $1.18, while shares in

Ford

(F) - Get Report

were down 2 cents to $5.47.