Many GOP senators have been clear that they want their health care bill to have more generous tax credits than the House bill and to soften its Medicaid expansion phaseout. But their hands may be tied: According to Senate budget rules, the upper chamber's bill must save at least as much as the House bill. And the changes some of these more moderate senators want cost money.
What to watch: If the Senate wants to spend more money on assistance for older and low-income people than the House did, it must also bring in more money. This could mean putting off the repeal of some of the Affordable Care Act taxes, or new revenue-raising methods altogether — like, for example, capping the tax exemption for employer insurance benefits (a step the House rejected).
The bottom line: "Something will have to give," said Ed Lorenzen, a senior adviser at the Committee for a Responsible Federal Budget.