Republicans hold a slim majority in the upper chamber, with 53 senators to the 47 who caucus with the Democrats. If all Democratic senators vote against the bill, as is expected, it will take only a handful of GOP rebels to defeat it.

Senate Republicans have offered warnings that President Donald Trump may need to adopt a softer approach than his usual strong-arm politics to pass his tax and spending bill in the upper chamber. Public barrages by Trump and his top aides against Senate GOP holdouts are complicating efforts to muscle through the House-passed measure that advances