In fact, a majority of the 46 Republicans in the Senate may end up lining up instead with their party leaders, who want to pass an emergency spending bill by September 30 that would avoid a federal government shutdown and would undercut Cruz's high-stakes effort to stop Obamacare.
"I intend to speak in support of defunding Obamacare until I am no longer able to stand," said the freshman Texas senator who has his eye on a 2016 run for president.
He went on to talk about his father "flippin pancakes," making "green eggs and ham," "the travesty of Obamacare," and, proudly, about his unpopularity among many fellow Republicans.
Practically every day, he said in his marathon speech, "I now pick up the newspaper to learn what a scoundrel I am."
It had the look and sound of an old-fashioned "filibuster" used traditionally by senators to block legislation, except that in this case, it won't.
Under Senate rules, Cruz must yield the floor for a procedural vote on Wednesday when Democrats and many Republicans are expected to band together to begin moving the must-do spending bill toward passage, likely on Sunday.
It will then go back to the House, which will have one day to pass the bill or find a compromise with the Senate. Unless new funding is quickly approved, a government shutdown would begin on Tuesday.
Republicans uniformly want to repeal Obamacare. But many see that as a political impossibility in the face of Democratic opposition and do not want to trigger a government shutdown in a battle that even Cruz has acknowledged is futile.
For the most part, Democrats sat back enjoying the display of a Republican in a dog fight with other Republicans.
Cruz has a following however. Club for Growth, a conservative group influential among Republicans, put senators on notice that it expected them to support Cruz's bid and block Democrats' from eliminating the provision to defund Obamacare.
But his fellow Republicans were moving in the other direction one day after the party's top two leaders in the Senate, Mitch McConnell and John Cornyn, refused to lend their support to Cruz.
Senator Orrin Hatch, the senior Republican on the Senate Finance Committee that oversees Obamacare, announced he would side with McConnell rather than Cruz.
Senator Lindsey Graham said he expects a majority of the Senate's 46 Republicans will reject Cruz's high-stakes maneuver that has been embraced by the Republican-led House of Representatives.
"I think most Republicans believe, no matter how sincere you are about defunding Obamacare, that this approach would blow up in our face," Graham told Reuters in a brief hallway interview on Capitol Hill.
A government shutdown could ruin the party's chances of winning back control of the Senate in the 2014 elections.
At the urging of Cruz and other legislators aligned with the anti-government Tea Party movement, the Republican-led House of Representatives passed the bill providing government funding but without money for Obamacare. Passage came on a party-line vote on Friday.
Since Cruz launched his bid, Republican senators and their aides have been unusually candid in their impatience with him, laying bare a deep split within the Republican Party.