NEW YORK (CNNMoney.com) - The head of the United Auto Workers union promised to work with bankrupt auto parts makers and troubled U.S. automakers to help turn around the struggling sector, but also said that the industry can not downsize itself to success.

Speaking at the union's convention in Las Vegas, UAW President Ron Gettelfinger said that working with General Motors (Research) and Ford Motor (Research) to cut health care costs was the most difficult thing he had done in his four-year tenure as head of the union, but said it was the right thing to do, despite some rank and file objections. Changes in the plan at Ford only narrowly won the approval of a majority of rank and file members.

United Auto Workers union President Ron Gettelfinger addresses the union's convention.

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And he warned members that more difficult choices are on the way.

"Like it or not, these challenges aren't the kind that can be ridden out," he said in his state of the union speech Monday. "They demand new and farsighted solutions — and we must be an integral part of developing those solutions."

But Gettelfinger, who is expected to be re-elected without serious opposition at this week's convention, also vowed that such concessions are not a sign that the union is weak or ready to surrender to management demands.

"We're not going to surrender. We're not going to lower our sights, give up our dreams, or give up our fight for a better world for our children and grandchildren," he said to applause from union delegates. "We're going to keep fighting for what we believe in, at the collective bargaining table, in the courts, in statehouses and the halls of Congress, in our communities, and where push comes to shove, on the picket lines."

The union reached agreement with bankrupt auto parts maker Delphi (Research) on Friday to offer buyouts to union members at the company in an effort to trim costs. The company also pushed back a bankruptcy court hearing at which it was to ask to throw out its union contracts.

The two moves were seen reducing the risk of a strike that could cripple not only Delphi but also General Motors (Research), its former parent and No. 1 customer. But Gettelfinger still had hard harsh words for Delphi management Monday.

He accused Delphi CEO Steve Miller as believing that "American workers need to get over the idea of having a middle-class lifestyle and resign themselves to barely scraping by."

He praised legislation that would prevent companies in bankruptcy court from cutting labor contracts at the same time that executives are getting new bonuses, and also allow bankruptcy court judges to consider a company's overseas' profits, not just its money-losing U.S. operations.

"Let me add that not all employers that are in bankruptcy fall into this category," he said, as he cited other auto parts makers such as "Collins and Aikman (Research), Dana (Research) and others (who) are working with our union and other unions to restructure without destroying their collective bargaining agreements and eliminating retiree health care and pension plans. And we applaud them for that."

The union boss said the union would push for incentives for the U.S. auto industry to build more alternative fuel vehicles. He also backed a so-called single-payer health care system in which there was a single government health insurance plan seen in many other countries rather than employer-based coverage.

"The UAW has long made the case that health care is a national problem that demands a national solution. It's not, as some people seem to believe, something that can be 'fixed' at the collective bargaining table," he said.

Related: UAW chief: Problems more serious than ever