Senate Majority Leader John Thune can afford to lose three Republican senators and still pass the bill, and there are more than that, right now, who have problems with it. Like the House, he will have to balance the concerns from moderate and conservative members of his conference.

The reforms could impact millions by tightening eligibility, shifting program costs, and limiting future benefit increases.

The Republican-led House narrowly passed President Donald Trump’s sweeping tax and spending bill late early Thursday morning, sending the package to the Senate where it is likely to be revised.