US President Barack Obama could sign a major health reform bill into law on Tuesday just as attention shifts to the Senate, which is expected to begin debating another round of changes to the landmark legislation, dpa reported. The sweeping overhaul aimed at expanding health coverage to about 32 million uninsured Americans was approved by the House of Representatives a little before midnight on Sunday, a major victory for Democrats who long made universal health care a top priority. But the House also backed a series of changes that must now go back to the US Senate for final approval. Obama is likely to sign the underlying bill on Tuesday, the New York Times reported, before helping get its final elements through the Senate later this week. The legislation emerged despite united Republican opposition, which argued that the most monumental changes to the health care sector in four decades were too costly and amounted to a dangerous government takeover.