Sen. Ted Cruz stood for hours on end Tuesday and into Wednesday this week making the case for defunding Obamacare.

It's a compelling case because Obamacare increasingly appears to be converting America into a nation of part-time workers, crushing the opportunity of businesses to expand and create new jobs, robbing millions of families and individuals of the doctors and health insurance President Obama promised they could keep, stifling medical innovation that could someday save countless lives, compromising the financial and medical privacy that was before sacrosanct, and in countless other ways subverting a private sector-based health care system that draws the lame, the ill and the injured from around the world.

And it is doing all of that even before its first full official day in effect.

Cruz has turned himself into a hero to many outside of Washington, and a thorn to many more inside the Beltway. Whether the Texas Republican's efforts – and those of his compatriots like Sen. Mike Lee, R-Utah, Sen. Marco Rubio, R-Fla., Sen. Rand Paul, R-Ky., Sen. Jeff Sessions, R-Ala., and others – prove a futile failure or an improbable success, the debate over defunding Obamacare has exposed the enduring influence of two men, Democrat Franklin D. Roosevelt and Republican Arthur Larson.

The former, of course, occupied the White House for all or part of four terms. His New Deal remade the federal government into the dominant factor in virtually every sphere of American public life.

Larson was Roosevelt’s most important GOP ally. An appointee of President Eisenhower, Larson’s best-selling 1954 book, “A Republican Looks at his Party,” coined the concept of “Modern Republicanism.”

As explained by FrumForum's Geoffrey Kabaservice in a 2009 post, the aim of Larson's brand of Republicanism was to make peace with FDR, “to rationalize and reform the New Deal rather than repeal it.” Republicans would not repeal the New Deal, they would simply deliver it more efficiently than Democrats.

For better or worse, Larson distilled the essential inspiration for the moderate wing of the GOP epitomized by Nelson Rockefeller and Gerald Ford against the grass-roots populism of Barry Goldwater and Ronald Reagan.

But Modern Republicanism also saddled its adherents with an impossible burden that has been highlighted by the present defunding debate: Except for a handful of northeastern states, political survival for moderate GOPers has since the 1960s required them to at least sound like they share the values and aims of the party’s populist conservative and libertarian grassroots base.

The GOP base has for decades supported political figures promising less government, not more, which makes anathema of Democrat expansions of the New Deal in programs like Obamacare and Republicans who can't or won't oppose them.

This conundrum explains the actions of Republicans like Senate Minority Leader Mitch McConnell of Kentucky and his top whip, Sen. John Cornyn of Texas against Cruz.

Here's how it will play out: McConnell and Cornyn will support – or at least not vigorously oppose - Senate Majority Leader Harry Reid’s forthcoming motion to cut off debate and silence Cruz.

Then, when the defunding issue is put to a vote (requiring only a simple majority to pass), they will “support” defunding, which will almost certainly be defeated on a straight-party line, 54-46.

Here’s the key: The motion to end debate will require 60 votes, which a unified Senate GOP can defeat. Doing so would preserve the House continuing resolution that defunds Obamacare and vindicate Cruz, at least temporarily, by preventing the second simple majority vote that Democrats will surely win.

By voting first to silence Cruz and then casting a doomed vote to defund Obamacare, McConnell, Cornyn and other Senate GOPers who follow their lead will appear to be opposing Obamacare, but in reality will effectively be protecting President Obama’s signature domestic policy achievement.

Somewhere, Roosevelt and Larson will be beaming, and not only because the New Deal is again protected and indeed expanded. They will be all smiles because they also know the GOP grassroots increasingly expects its leaders in Washington to both talk and vote for less government.

That expectation is why a growing number of GOP incumbents, including McConnell, are being "primaried" by Tea Party rivals. In other words, adherence to Modern Republicanism long ago almost certainly made a split in the GOP all but inevitable and made it seem all-but-impossible to restore limited government.