WASHINGTON -- Wal-Mart is the latest in a line of traditionally Republican-leaning businesses to embrace key portions of President Barack Obama's bid to overhaul health care, a trend that could complicate opponents' efforts to build a united front when Congress ramps up its work on the issue this summer.

Wal-Mart, the nation's largest private employer, on Tuesday endorsed the idea of requiring large companies to offer health insurance to their workers. The proposal is central to Obama's hopes of covering the nation's nearly 50 million uninsured and is disliked by some business groups.

Wal-Mart was joined by a major labor union that sometimes has criticized the company's relatively stingy employee benefits.

The big retailer is not the only one-time opponent of health care revisions to embrace at least some aspects of Obama's proposals. The major group representing pharmaceutical makers recently said it would reduce senior citizens' costs for prescription drugs by $80 billion over 10 years. And major groups representing doctors, hospitals and other providers have pledged to reduce health care costs by large amounts.

Nearly all these groups, by varying degrees, opposed efforts to overhaul the nation's health care system during the Clinton administration in 1993-94. Moreover, Wal-Mart and its officials have given far more in political contributions over the past decade to Republicans than to Democrats. The same is true of the pharmaceutical industry and several other health-related groups.

But with better prospects for a health care bill this time -- and the public favoring overhaul, many businesses and industries want to be part of the final legislation rather than left out.

"We are for an employer mandate which is fair and broad in its coverage," Wal-Mart said in a letter to congressional and administration officials. "Any alternative to an employer mandate should not create barriers to hiring entry-level employees."

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