The early primaries usually winnow presidential fields because each one tests aspects of a candidacy, and because only victories keep the money flowing.

But while this Republican field has winnowed, it hasn’t shrunk as much as some would like. Part of the answer involves the existence of super PAC money, which allows a handful of contributors to keep a candidacy alive. But maybe even more important this time is the shape of the field and the nature of the front-runner.

Donald Trump is such an unconventional front-runner – he has never held office, is a celebrity and is devious and inflammatory — that other candidates believe that if they simply stay alive, they can become “the” alternative to Trump, thereby giving them a shot at the Republican nomination.

Both Texas Sen. Ted Cruz and Ohio Gov. John Kasich still have “scenarios” for victory, and while neither one is very plausible, that does not seem to matter right now.

Cruz’s strategy was and is based on becoming “the” surviving conservative (and evangelical) candidate in race. His victory in Iowa seemed to validate that strategy, especially since the Texas senator (27.6 percent), Trump (24.3 percent) and Marco Rubio (23.1 percent) distanced themselves so much from the rest of the field.

But Cruz’s relatively weak third-place showing in South Carolina, even after social conservatives Mike Huckabee, Rick Santorum and Bobby Jindal had exited the race, raises questions about the Texan’s appeal, as does polling that shows Trump performing well in many of the March 1 primaries that Cruz had once expected to sweep.

Cruz can receive a jolt of delegates from Texas and other Southern states on Tuesday, but unless he has established himself as the conservative alternative to Trump, the Texan is toast because nine of the 12 states with the largest percentage of self-identified conservatives (according to Gallup), will have selected their delegates by March 8.

Alabama, Arkansas, Tennessee and Oklahoma have March 1 contests, Kentucky and Louisiana are March 5, Mississippi and Idaho are March 8, and South Carolina held its primary last week. Since North Dakota will be sending unpledged delegates to Cleveland, that leaves only Utah (March 22), Wyoming (April 9) and Montana (June 7) as the most conservative states to select delegates after March 8.

So, Cruz will soon be running in less religious, more pragmatic territory – places where his Texas twang, social conservatism and uncompromising approach are less likely to resonate.

Kasich, on the other hand, is relying on a Great Lakes strategy that includes strong showings in Michigan (March 8), and Ohio and Illinois (March 15). He is betting this will keep his campaign alive, even though he isn’t a factor in most of the early March contests. Polls generally show him running in the mid-single digits in Texas, Oklahoma, Georgia, North Carolina, Florida and Virginia.

In the first four contests, Kasich finished tied for seventh (Iowa), second (New Hampshire), fifth (South Carolina) and fifth and last (Nevada).

In contrast, Rubio, who has two second-place finishes, a third and a fifth in the first four contests, is competing virtually everywhere and is building support in most states, according to state polls. More importantly, he should add to his delegate total on Tuesday.

Essentially, Kasich is following a modified Giuliani strategy.

Former New York Mayor Rudy Giuliani tried to jumpstart his presidential campaign on January 29, 2008, almost a full month after the fight for the GOP campaign began with the Iowa caucuses on January 3.

Giuliani eventually understood that serious contenders cannot pick and choose where to run. They need to compete everywhere. Giuliani’s invisible showings in the first seven contests made him increasingly irrelevant in Florida, and his all-or-nothing effort fell far short when he drew just 15 percent of the vote, for a third-place finish, in the Sunshine State primary.

Kasich’s situation is a bit different, both because his home state, as well as two, large neighboring states, are part of his strategy and because Trump is so controversial. That makes his prospects better than were Giuliani’s. But not by much.

The only way for the Ohio governor to become relevant in the GOP race is if he wins Illinois and winner-take-all Ohio, while Rubio loses in Florida to Trump.

But if Trump wins the Sunshine State, after piling up delegates during the first two weeks of March, it is difficult to see how Kasich can overtake him. Florida, with the third-largest delegation at the convention, is a winner-take-all state.

In spite of the media’s hand-wringing, the bottom line in the GOP contest has not changed this week. Trump is the front-runner not because of his broad appeal or because he is being embraced by his party, but because he can get a third of the vote in a crowded race. That is enough in a field of four or five contenders, but not in a two-man race.

Trump’s increasingly bizarre behavior and unpresidential statements probably won’t shake those true believers who support him, but they limit his ability to attract new supporters.

If the Republican field never narrows, Trump will likely become his party’s nominee. But if it does, the front-runner will become much more vulnerable, most likely to Rubio, who has spent the last few days trying to make himself into the alternative by taking Trump on directly and with vigor, and who could surprise on Super Tuesday.

One thing seems certain: If Donald Trump does not win the nomination outright before Cleveland, he will not be the Republican nominee.

Roll Call Race Ratings Map: Ratings for Every House and Senate Race in 2016

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