Thune: CLASS repeal dead on arrival in the Senate

"I think we'd get a majority; I don't think we'd get 60," Thune said.

Still, Thune said, the House vote would create "momentum" in the Senate, where Democrats would be put on the spot. Republicans hope to embarrass Democrats by forcing them to support a voluntary payroll tax deduction program that the Obama administration itself has said is unsustainable.

Even getting a simple majority in the Senate would be a tall order. Republicans would need to persuade at least four Democrats to vote for repeal and break party unity, something they've failed to do in the House so far. Only four House Democrats — Reps. Jim MathesonJames (Jim) David MathesonUtah redistricting reform measure likely to qualify for ballot Trump's budget targets affordable, reliable power Work begins on T infrastructure plan MORE (Utah), Mike Ross (Ark.), John BarrowJohn Jenkins BarrowOur democracy can’t afford to cut legal aid services from the budget Dem files Ethics complaint on Benghazi panel Barrow thanks staff in farewell speech MORE (Ga.) and Ron KindRonald (Ron) James KindCongress must defend role in international trade It's time for Congress to step in and stop Trump's trade abuses Lobbying world MORE (Wis.) — voted for repeal when it came up in committee, and the first three had voted against the reform law in the first place.