In his victory speech in South Carolina Saturday night Donald Trump never mentioned Jeb Bush. He should have, if only to say "thanks, Jeb! I couldn't have done this without you."   

Bush made Trump possible, maybe even inevitable.

Bush entered the race a year ago as the unabashed friend of the Republican "donor class." His strategy for winning the Republican nomination was simple and straightforward: Raise a big pile of cash, so big that anyone else thinking of running will think again.

Some inside the campaign called it "shock and awe," but it now appears to have been a colossal blunder. Instead, its main impact was to galvanize Tea Party activists against Bush and eventually drive them into the open arms of Trump.

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Jeb Bush takes the stage in Columbia, S.C., with supporter Lindsey Graham before announcing he was suspending his presidential campaign. (Mark Makela/Getty Images)

Bush's exit from the race is a sweet victory for Tea Party Trump followers — a spectacular trophy in their raid on the Republican establishment.

Now that South Carolina is in his win column history moves over to Trump's side too.

Every Republican who, like Trump, has won both the New Hampshire and South Carolina primaries has gone on to win the party's nomination.

As usual Trump has arrived where he is while defying normal political behaviour.

He won despite his South Carolina debate performance last week, his worst since the campaign began.

He won despite getting into a tangle with the Pope just days before the vote.

He won despite former President George W. Bush and his revered mother Barbara campaigning for Jeb; South Carolina Governor Nikki Haley endorsing Marco Rubio; Ted Cruz's fit with the state's abundant evangelical Christians.

And so to many, Trump now looks unstoppable, and if this were any other election campaign there wouldn't be much argument about that.

High number of undecided Republicans

But there persists a feeling among some that most of the 65 per cent of Republicans who haven't yet moved to support Trump never will.

They believe Trump is an unacceptable nominee for most of their party.

S. Carolina Republicans

South Carolina is sending 50 delegates to the Republicans' national convention. In the two previous battlegrounds there were just 30 delegates up for grabs for the party's contenders in Iowa and 23 in New Hampshire. (CBC)

They've pinned their hopes on what they see as the "high floor, low ceiling" of Trump's support — that, while Trump always seems to have 30 to 35 per cent in the polls (his high floor), he rarely has more than that (his low ceiling).

Logically, goes their theory, once two or three more candidates follow Bush off the island, the anti-Trump people will consolidate behind whoever's still left and that person — Cruz or Rubio, probably — will start winning some primaries.

Trump shared his own thoughts on the theory and the people who believe in it, Saturday night.

'They don't understand that as people drop out, I'm going to get a lot of those votes also.' - Donald Trump

"They don't understand that as people drop out, I'm going to get a lot of those votes also. You don't just add them together."

If he's right, then he's unstoppable.

And as we know, he's been more right than wrong about this sort of thing lately.

5 Republicans may remain for Super Tuesday

In any event, the winnowing of the Republican field continues with the opposite of urgency. It looks as though there will still be five candidates — Trump, Rubio, Cruz, John Kasich and Ben Carson — going into Super Tuesday on March 1.

Super Tuesday is the biggest delegate selection night of the campaign. Republicans will have 11 state primaries, mostly in the South, and a caucus in Alaska.

There isn't much recent polling in many of those states, but where there is, it invariably shows Trump leading.

And as long as the field against him remains divided, his high floor/low ceiling 30-35 per cent will get him where he wants to go.

The Democrats are sorting themselves out in a different way.

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Democratic presidential candidate Hillary Clinton greets supporters, as her husband, former president Bill Clinton, looks on at Caesars Palace in Las Vegas on Saturday. She claimed victory over Democratic rival Sen. Bernie Sanders in the Nevada Democratic caucuses. (Justin Sullivan/Getty Images)

Hillary Clinton won an important victory in the Nevada caucuses.

It was close, but she won comfortably enough that if she wins South Carolina next weekend, as expected, it's going to be tough for Bernie Sanders to make a convincing case that he can still deliver "one of the biggest political upsets in the history of the United States."

He insists they are still almost tied in the delegate count, but a broader read reveals that she has an enormous advantage among the super-delegates that make up the party establishment.

Still, Sanders's impact on the race is irreversible. Clinton has been changed by it. 

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Democratic presidential candidate Sen. Bernie Sanders concedes victory to Hillary Clinton in a speech at the Henderson Pavilion in Henderson, Nevada. (Ethan Miller/Getty Images)

Stylistically, she's begun to experiment with personal pronouns. She's exploring beyond the first person singular and adding more "we" to her story of "I".

Substantively, she's appealing directly to the demographic that supports Sanders, learning what they're about and promising that things such as student debt will be a priority for her.

But the campaign has exposed her vulnerabilities too. She hasn't been repudiated the way Jeb Bush was, but she's still catching up to what's going among voters in America.