Hours after Republicans barely mustered enough votes to start debate on a House-passed GOP bill designed to overhaul the Obama health law, the Senate easily rejected one plan put forward by Republican Senators, as GOP leaders continued to struggle to figure out how to forge a health care bill that could win final approval on the Senate floor later this week.

The first casualty was an amended version of the "Better Care" plan from GOP leaders - along with additions from Sen. Rob Portman (R-OH), who wanted to add back $100 billion in Medicaid funding, and Sen. Ted Cruz (R-TX), who pressed for his 'Consumer Freedom Amendment,' which would let insurance companies that sell regular Obamacare plans also offer lower-cost plans with less health coverage.

"What we know won't work is Obamacare," Cruz argued on the Senate floor.

But the Cruz plan ran afoul of strict Senate budgetary rules, and needed 60 votes for approval. Republicans were not even able to muster a majority, getting only 43 votes, as nine GOP Senators voted against the plan.

"We can't give up," said Sen. Joni Ernst (R-IA), as Republicans fully acknowledged they weren't sure where the debate was headed in terms of the details of a GOP health care overhaul bill.

“It will depend on what’s in the final bill, which nobody has any idea as to how that’s going to end up,” said Sen. Johnny Isakson (R-GA).

"It's going to be interesting to see what happens," said Sen. Orrin Hatch (R-UT). "It's kind of up in the air right now."

Opponents of the Republican effort were still ramping up their efforts to push back against GOP health care plans, worried that something will pass late this week by the narrowest of margins.

"The voting now means nothing," said Andy Slavitt, who ran the operations of the Obamacare exchanges under the Obama Administration. "The backroom deals mean everything."

More votes were set for Wednesday, as Republicans were desperately seeking a way to get almost anything approved this week - and then send that on to House-Senate negotiations.

One plan getting attention was being labeled the "skinny repeal" - zeroing out the individual and employer mandate penalties, and repealing the medical device tax, while leaving all other provisions alone.

The idea was that might be the ultimate GOP fall back plan, but still allow the health care effort to survive, with negotiations on a final bill taking place during the August break.